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For other information, see the Ghostscript overview and, if necessary, how to install Ghostscript.

Invoking Ghostscript

This document describes how to use the command line Ghostscript client. Ghostscript is also used as a general engine inside other applications (for viewing files for example). Please refer to the documentation for those applications for using Ghostscript in other contexts.

The command line to invoke Ghostscript is essentially the same on all systems, although the name of the executable program itself may differ among systems. For instance, to invoke Ghostscript on unix-like systems type:

gs [options] {filename 1} ... [options] {filename N} ...

Here are some basic examples. The details of how these work are described below.

To view a file:

gs -dSAFER -dBATCH document.pdf

You'll be prompted to press return between pages.

To convert a figure to an image file:

gs -dSAFER -dBATCH -dNOPAUSE -sDEVICE=png16m -dGraphicsAlphaBits=4 \
    -sOutputFile=tiger.png tiger.eps

To render the same image at 300 dpi:

gs -dSAFER -dBATCH -dNOPAUSE -sDEVICE=png16m -r300 \
                -sOutputFile=tiger_300.png tiger.eps

To render a figure in grayscale:

gs -dSAFER -dBATCH -dNOPAUSE -sDEVICE=pnggray -sOutputFile=figure.png figure.pdf

To rasterize a whole document:

gs -dSAFER -dBATCH -dNOPAUSE -sDEVICE=pgmraw -r150 \
                -dTextAlphaBits=4 -sOutputFile='paper-%00d.pgm' paper.ps

There are also a number of utility scripts for common to convert a PostScript document to PDF:

ps2pdf file.ps

The output is saved as file.pdf.

There are other utility scripts besides ps2pdf, including pdf2ps, ps2epsi, pdf2dsc, ps2ascii, ps2ps and ps2ps2. These just call Ghostscript with the appropriate (if complicated) set of options. You can use the 'ps2' set with eps files.

Ghostscript is capable of interpreting PostScript, encapsulated PostScript (EPS), DOS EPS (EPSF), and Adobe Portable Document Format (PDF). The interpreter reads and executes the files in sequence, using the method described under "File searching" to find them.

The interpreter runs in interactive mode by default. After processing the files given on the command line (if any) it reads further lines of PostScript language commands from the primary input stream, normally the keyboard, interpreting each line separately. To quit the interpreter, type "quit". The -dBATCH -dNOPAUSE options in the examples above disable the interactive prompting. The interpreter also quits gracefully if it encounters end-of-file or control-C.

The interpreter recognizes many options. An option may appear anywhere in the command line, and applies to all files named after it on the line. Many of them include "=" followed by a parameter. The most important are described in detail here. Please see the reference sections on options and devices for a more complete listing.

Help at the command line: gs -h

You can get a brief help message by invoking Ghostscript with the -h or -? switch, like this:

gs -h
gs -?

The message shows for that version of the Ghostscript executable:

  • the version and release information
  • the general format of the command line
  • a few of the most useful options
  • the formats it can interpret
  • the available output devices
  • the search path
  • the bug report address

On other systems the executable may have a different name:

System Invocation Name
Unix gs
VMS gs
MS Windows 95 and later gswin32.exe gswin32c.exe gswin64.exe gswin64c.exe
OS/2 gsos2

On Windows, the two digit number indicates the word length of the system for which the binary was built (so gswin32.exe is for x86 Windows systems, whilst gswin64.exe is for x86_64 Windows systems). And the "c" suffix indicates a Windows console based binary (note that the "display device" window will still appear).

Selecting an output device

Ghostscript has a notion of 'output devices' which handle saving or displaying the results in a particular format. Ghostscript comes with a diverse variety of such devices supporting vector and raster file output, screen display, driving various printers and communicating with other applications.

The command line option '-sDEVICE=device' selects which output device Ghostscript should use. If this option isn't given the default device (usually a display device) is used. Ghostscript's built-in help message (gs -h) lists the available output devices. For complete description of the devices distributed with Ghostscript and their options, please see the devices section of the documentation.

Note that this switch must precede the name of the first input file, and only its first use has any effect. For example, for printer output in a configuration that includes an Epson printer driver, instead of just 'gs myfile.ps' you might use

gs -sDEVICE=epson myfile.ps

The output device can also be set through the GS_DEVICE environment variable.

Once you invoke Ghostscript you can also find out what devices are available by typing 'devicenames ==' at the interactive prompt. You can set the output device and process a file from the interactive prompt as well:

(epson) selectdevice
(myfile.ps) run

All output then goes to the Epson printer instead of the display until you do something to change devices. You can switch devices at any time by using the selectdevice procedure, for instance like one of these:

(x11alpha) selectdevice
(epson) selectdevice

Output resolution

Some printers can print at several different resolutions, letting you balance resolution against printing speed. To select the resolution on such a printer, use the -r switch:

gs -sDEVICE=printer -rXRESxYRES

where XRES and YRES are the requested number of dots (or pixels) per inch. Where the two resolutions are same, as is the common case, you can simply use -rres.

The -r option is also useful for controlling the density of pixels when rasterizing to an image file. It is used this way in the examples at the beginning of this document.

Output to files

Ghostscript also allows you to control where it sends its output. With a display device this isn't necessary as the device handles presenting the output on screen internally. Some specialized printer drivers operate this way as well, but most devices are general and need to be directed to a particular file or printer.

To send the output to a file, use the -sOutputFile= switch or the -o switch (below). For instance, to direct all output into the file ABC.xyz, use

gs -sOutputFile=ABC.xyz

When printing on MS Windows systems, output normally goes directly to the printer, PRN. On Unix and VMS systems it normally goes to a temporary file which is sent to the printer in a separate step. When using Ghostscript as a file rasterizer (converting PostScript or PDF to a raster image format) you will of course want to specify an appropriately named file for the output.

Ghostscript also accepts the special filename '-' which indicates the output should be written to standard output (the command shell).

Be aware that filenames beginning with the character % have a special meaning in PostScript. If you need to specify a file name that actually begins with %, you must prepend the %os% filedevice explicitly. For example to output to a file named %abc, you need to specify

gs -sOutputFile=%os%%abc

Please see Ghostscript and the PostScript Language and the PostScript Language Reference Manual for more details on % and filedevices.

Note that on MS Windows systems, the % character also has a special meaning for the command processor (shell), so you will have to double it.

gs -sOutputFile=%%os%%%%abc (on MS Windows)

Note, some devices (e.g. pdfwrite, ps2write, ...) only write the output file upon exit, but changing the OutputFile device parameter will cause these devices to emit the pages received up to that point and then open the new file name given by OutputFile.

For example, in order to create two PDF files from a single invocation of ghostscript the following can be used:

gs -sDEVICE=pdfwrite -o tiger.pdf examples/tiger.eps -c "<< /OutputFile (colorcir.pdf) >> setpagedevice" -f examples/colorcir.ps

One page per file

Specifying a single output file works fine for printing and rasterizing figures, but sometimes you want images of each page of a multi-page document. You can tell Ghostscript to put each page of output in a series of similarly named files. To do this place a template '%d' in the filename which Ghostscript will replace with the page number.

Note: Since the % character is used to precede the page number format specification, in order to represent a file name that contains a %, double % characters must be used. For example for the file my%foo the OutputFile string needs to be my%%foo.

The format can in fact be more involved than a simple '%d'. The format specifier is of a form similar to the C printf format. The general form supported is:

            %[flags][width][.precision][l]type

    where:  flags    is one of:  #+-
            type     is one of:  diuoxX

For more information, please refer to documentation on the C printf format specifications. Some examples are:

-sOutputFile=ABC-%d.png
produces 'ABC-1.png', ... , 'ABC-10.png', ..
-sOutputFile=ABC-%03d.pgm
produces 'ABC-001.pgm', ... , 'ABC-010.pgm', ...
-sOutputFile=ABC_p%04d.tiff
produces 'ABC_p0001.tiff', ... , 'ABC_p0510.tiff', ... , 'ABC_p5238.tiff'

Note, however that the one page per file feature may not supported by all devices. Also, since some devices write output files when opened, there may be an extra blank page written (pdfwrite, ps2write, eps2write, pxlmono, pxlcolor, ...).

As noted above, when using MS Windows console (command.com or cmd.exe), you will have to double the % character since the % is used by that shell to prefix variables for substitution, e.g.,

gswin32c -sOutputFile=ABC%%03d.xyz

-o option:

As a convenient shorthand you can use the -o option followed by the output file specification as discussed above. The -o option also sets the -dBATCH and -dNOPAUSE options. This is intended to be a quick way to invoke ghostscript to convert one or more input files.

For instance, to convert somefile.ps to JPEG image files, one per page, use:

gs -sDEVICE=jpeg -o out-%d.jpg somefile.ps

is equivalent to:

gs -sDEVICE=jpeg -sOutputFile=out-%d.jpg -dBATCH -dNOPAUSE somefile.ps

Choosing paper size

Ghostscript is distributed configured to use U.S. letter paper as its default page size. There are two ways to select other paper sizes from the command line:

  • If the desired paper size is listed in the section on paper sizes known to Ghostscript below, you can select it as the default paper size for a single invocation of Ghostscript by using the -sPAPERSIZE= switch, for instance
    • -sPAPERSIZE=a4
    -sPAPERSIZE=legal
  • Otherwise you can set the page size using the pair of switches
    • -dDEVICEWIDTHPOINTS=w -dDEVICEHEIGHTPOINTS=h

    Where w be the desired paper width and h be the desired paper height in points (units of 1/72 of an inch).

Individual documents can (and often do) specify a paper size, which takes precedence over the default size. To force a specific paper size and ignore the paper size specified in the document, select a paper size as just described, and also include the -dFIXEDMEDIA switch on the command line.

The default set of paper sizes will be included in the currentpagedevice in the InputAttributes dictionary with each paper size as one of the entries. The last entry in the dictionary (which has numeric keys) is a non-standard (Ghostscript extension) type of PageSize where the array has four elements rather than the standard two elements. This four element array represents a page size range where the first two elements are the lower bound of the range and the second two are the upper bound. By default these are [0, 0] for the lower bound and [16#fffff, 16#fffff] for the upper bound.

The range type of PageSize is intended to allow flexible page size sepcification for non-printer file formats such as JPEG, PNG, TIFF, EPS, ...

For actual printers, either the entire InputAttributes dictionary should be replaced or the range type entry should not be included. To simplify using the default page sizes in the InputAttributes dictionary, the command line option -dNORANGEPAGESIZE can be used. Using this option will result in automatic rotation of the document page if the requested page size matches one of the default page sizes.

When the -dFIXEDMEDIA switch is given on the command line, the InputAttributes dictionary will only be populated with the single page size. This allows the -dPSFitPage option to fit the page size requested in a PostScript file to be rotated, scaled and centered for the best fit on the specified page.

Changing the installed default paper size

You can change the installed default paper size on an installed version of Ghostscript, by editing the initialization file gs_init.ps. This file is usually in the Resource/Init directory somewhere in the search path. See the section on finding files for details.

Find the line

% /DEFAULTPAPERSIZE (a4) def

Then to make A4 the default paper size, uncomment the line to change this to

/DEFAULTPAPERSIZE (a4) def

For a4 you can substitute any paper size Ghostscript knows.

This supecedes the previous method of uncommenting the line % (a4) ....

Sometimes the initialization files are compiled into Ghostscript and cannot be changed.

On Windows and some Linux builds, the default paper size will be selected to be a4 or letter depending on the locale.

Interacting with pipes

As noted above, input files are normally specified on the command line. However, one can also "pipe" input into Ghostscript from another program by using the special file name '-' which is interpreted as standard input. Examples:

{some program producing ps} | gs [options] -
zcat paper.ps.gz | gs -

When Ghostscript finishes reading from the pipe, it quits rather than going into interactive mode. Because of this, options and files after the '-' in the command line will be ignored.

On Unix and MS Windows systems you can send output to a pipe in the same way. For example, to pipe the output to lpr, use the command

gs -q -sOutputFile=- | lpr

In this case you must also use the -q switch to prevent Ghostscript from writing messages to standard output which become mixed with the intended output stream.

Also, using the -sstdout=%stderr option is useful, particularly with input from PostScript files that may print to stdout.

Similar results can be obtained with the %stdout and %pipe% filedevices. The example above would become

gs -sOutputFile=%stdout -q | lpr
or
gs -sOutputFile=%pipe%lpr

(again, doubling the % character on MS Windows systems.)

In the last case, -q isn't necessary since Ghostscript handles the pipe itself and messages sent to stdout will be printed as normal.

Using Ghostscript with PDF files

Ghostscript is normally built to interpret both PostScript and PDF files, examining each file to determine automatically whether its contents are PDF or PostScript. All the normal switches and procedures for interpreting PostScript files also apply to PDF files, with a few exceptions. In addition, the pdf2ps utility uses Ghostscript to convert PDF to (Level 2) PostScript.

Switches for PDF files

Here are some command line options specific to PDF

-dPDFFitPage
Rather than selecting a PageSize given by the PDF MediaBox, BleedBox (see -dUseBleedBox), TrimBox (see -dUseTrimBox), ArtBox (see -dUseArtBox), or CropBox (see -dUseCropBox), the PDF file will be scaled to fit the current device page size (usually the default page size).

This is useful for creating fixed size images of PDF files that may have a variety of page sizes, for example thumbnail images.

This option is also set by the -dFitPage option.

-dPrinted
-dPrinted=false
Determines whether the file should be displayed or printed using the "screen" or "printer" options for annotations and images. With -dPrinted, the output will use the file's "print" options; with -dPrinted=false, the output will use the file's "screen" options. If neither of these is specified, the output will use the screen options for any output device that doesn't have an OutputFile parameter, and the printer options for devices that do have this parameter.
-dUseBleedBox
Sets the page size to the BleedBox rather than the MediaBox. defines the region to which the contents of the page should be clipped when output in a production environment. This may include any extra bleed area needed to accommodate the physical limitations of cutting, folding, and trimming equipment. The actual printed page may include printing marks that fall outside the bleed box.
-dUseTrimBox
Sets the page size to the TrimBox rather than the MediaBox. The trim box defines the intended dimensions of the finished page after trimming. Some files have a TrimBox that is smaller than the MediaBox and may include white space, registration or cutting marks outside the CropBox. Using this option simulates appearance of the finished printed page.
-dUseArtBox
Sets the page size to the ArtBox rather than the MediaBox. The art box defines the extent of the page's meaningful content (including potential white space) as intended by the page's creator. The art box is likely to be the smallest box. It can be useful when one wants to crop the page as much as possible without losing the content.
-dUseCropBox
Sets the page size to the CropBox rather than the MediaBox. Unlike the other "page boundary" boxes, CropBox does not have a defined meaning, it simply provides a rectangle to which the page contents will be clipped (cropped). By convention, it is often, but not exclusively, used to aid the positioning of content on the (usually larger, in these cases) media.
-sPDFPassword=password
Sets the user or owner password to be used in decoding encrypted PDF files. For files created with encryption method 4 or earlier, the password is an arbitrary string of bytes; with encryption method 5 or later, it should be text in either UTF-8 or your locale's character set (Ghostscript tries both).
-dShowAnnots=false
Don't enumerate annotations associated with the page Annots key. Annotations are shown by default.

In addition, finer control is available by defining an array /ShowAnnotTypes. Annotation types listed in this array will be drawn, whilst those not listed will not be drawn.

To use this feature: -c "/ShowAnnotTypes [....] def" -f <input file>
Where the array can contain one or more of the following names: /Stamp, /Squiggly, /Underline, /Link, /Text, /Highlight, /Ink, /FreeText, /StrikeOut and /stamp_dict.

For example, adding the follow to the command line: -c "/ShowAnnotTypes [/Text /UnderLine] def" -f <input file>
would draw only annotations with the subtypes "Text" and "UnderLine"

-dShowAcroForm=false
Don't show annotations from the Interactive Form Dictionary (AcroForm dictionary). By default, AcroForm processing is now enabled because Adobe Acrobat does this. This option is provided to restore the previous behavior which corresponded to older Acrobat.
-dNoUserUnit
Ignore UserUnit parameter. This may be useful for backward compatibility with old versions of Ghostscript and Adobe Acrobat, or for processing files with large values of UserUnit that otherwise exceed implementation limits.
-dRENDERTTNOTDEF
If a glyph is not present in a font the normal behaviour is to use the /.notdef glyph instead. On TrueType fonts, this is often a hollow sqaure. Under some conditions Acrobat does not do this, instead leaving a gap equivalent to the width of the missing glyph, or the width of the /.notdef glyph if no /Widths array is present. Ghostscript now attempts to mimic this undocumented feature using a user parameter RenderTTNotdef. The PDF interpreter sets this user parameter to the value of RENDERTTNOTDEF in systemdict, when rendering PDF files. To restore rendering of /.notdef glyphs from TrueType fonts in PDF files, set this parameter to true.

These command line options are no longer specific to PDF, but have some specific differences with PDF files

-dFirstPage=pagenumber
Begin on the designated page of the document. Pages of all documents in PDF collections are numbered sequentionally.
-dLastPage=pagenumber
Stop after the designated page of the document. Pages of all documents in PDF collections are numbered sequentionally.
-sPageList=pagenumber
There are three possible values for this; even, odd or a list of pages to be processed. A list can include single pages or ranges of pages. Ranges of pages use the minus sign '-', individual pages and ranges of pages are separated by commas ','. A trailing minus '-' means process all remaining pages. For example; 

-sPageList=1,3,5 indicates that pages 1, 3 and 5 should be processed.
-sPageList=5-10 indicates that pages 5, 6, 7, 8, 9 and 10 should be processed.
-sPageList=1,5-10,12- indicates that pages 1, 5, 6, 7, 8, 9, 10 and 12 onwards should be processed.
Note: Use of PageList overrides FirstPage and/or LastPage, if you set these as well as PageList they will be ignored. The list of pages should be given in increasing order, you cannot process pages out of order and inserting higher numbered pages before lower numbered pages in the list will generate an error.

The PDF interpreter and the other language interpreters handle these in slightly different ways. Because PDF files enable random access to pages in the document the PDF inerpreter only interprets and renders the required pages. PCL and PostScript cannot be handled in ths way, and so all the pages must be interpreted. However only the requested pages are rendered, which can still lead to savings in time. Be aware that using the '%d' syntax for OutputFile does not reflect the page number in the original document. If you chose (for example) to process even pages by using -sPageList=even, then the output of -sOutputFile=out%d.png would still be out0.png, out1.png, out2.png etc......

Because the PostScript and PCL interpreters cannot determine when a document terminates, sending multple files as input on the command line does not reset the PageList between each document, each page in the second and subsequent documents is treated as following on directly from the last page in the first document. The PDF interpreter, however, does not work this way. Since it knows about individual PDF files the PageList is applied to each PDF file separately. So if you were to set -sPageList=1,2 and then send two PDF files, the result would be pages 1 and 2 from the first file, and then pages 1 and 2 from the second file. The PostScript interpreter, by contrast, would only render pages 1 and 2 from the first file. This means you must exercise caution when using this switch, and probably should not use it at all when processing a mixture of PostScript and PDF files on the same command line.

The XPS language like the PDF language allows random access to pages. The XPS interpreter handles all the PageList cases discussed above. It also handles cases such as: 

-sPageList=1,2,1,2 indicates repeated pages.  Pages processed in order 1, 2, 1, 2.
-sPageList=10-5 indicates pages will be processed in the order 10, 9, 8, 7, 6, 5.
-sPageList=1-,-1 indicates first processing from page 1 to end and then from end to page 1.
In addition, the XPS interpreter allows the use of a -dLastPage < -dFirstPage. In this case the pages will be processed backwards from LastPage to FirstPage.

Problems interpreting a PDF file

Occasionally you may try to read or print a 'PDF' file that Ghostscript doesn't recognize as PDF, even though the same file can be opened and interpreted by an Adobe Acrobat viewer. In many cases, this is because of incorrectly generated PDF. Acrobat tends to be very forgiving of invalid PDF files. Ghostscript tends to expect files to conform to the standard. For example, even though valid PDF files must begin with %PDF, Acrobat will scan the first 1000 bytes or so for this string, and ignore any preceding garbage.

In the past, Ghostscript's policy has been to simply fail with an error message when confronted with these files. This policy has, no doubt, encouraged PDF generators to be more careful. However, we now recognize that this behavior is not very friendly for people who just want to use Ghostscript to view or print PDF files. Our new policy is to try to render broken PDF's, and also to print a warning, so that Ghostscript is still useful as a sanity-check for invalid files.

PDF files from standard input

The PDF language, unlike the PostScript language, inherently requires random access to the file. If you provide PDF to standard input using the special filename '-', Ghostscript will copy it to a temporary file before interpreting the PDF.

Using Ghostscript with EPS files

Encapsulated PostScript (EPS) files are intended to be incorporated in other PostScript documents and may not display or print on their own. An EPS file must conform to the Document Structuring Conventions, must include a %%BoundingBox line to indicate the rectangle in which it will draw, must not use PostScript commands which will interfere with the document importing the EPS, and can have either zero pages or one page. Ghostscript has support for handling EPS files, but requires that the %%BoundingBox be in the header, not the trailer. To customize EPS handling, see EPS parameters.

For the official description of the EPS file format, please refer to the Adobe documentation in their tech note #5002. It is available from: http://partners.adobe.com/public/developer/ps/index_specs.html

Using Ghostscript with overprinting and spot colors

In general with PostScript and PDF interpreters, the handling of overprinting and spot colors depends upon the process color model of the output device. Devices that produce gray or RGB output have an additive process color model. Devices which produce CMYK output have a subtractive process color model. Devices may, or may not, have support for spot colors.

Note: The differences in appearance of files with overprinting and spot colors caused by the differences in the color model of the output device are part of the PostScript and PDF specifications. They are not due to a limitation in the implementation of Ghostscript or its output devices.

With devices which use a subtractive process color model, both PostScript and PDF allow the drawing of objects using colorants (inks) for one or more planes without affecting the data for the remaining colorants. Thus the inks for one object may overprint the inks for another object. In some cases this produces a transparency like effect. (The effects of overprinting should not be confused with the PDF 1.4 blending operations which are supported for all output devices.) Overprinting is not allowed for devices with an additive process color model. With files that use overprinting, the appearance of the resulting image can differ between devices which produce RGB output versus devices which produce CMYK output. Ghostscript automatically overprints (if needed) when the output device uses a subtractive process color model. For example, if the file is using overprinting, differences can be seen in the appearance of the output from the tiff24nc and tiff32nc devices which use an RGB and a CMYK process color models.

Most of the Ghostscript output devices do not have file formats which support spot colors. Instead spot colors are converted using the tint transform function contained within the color space definition.. However there are several devices which have support for spot colors. The PSD format (Adobe Photoshop) produced by the psdcmyk device contains both the raster data plus an equivalent CMYK color for each spot color. This allows Photoshop to simulate the appearance of the spot colors. The display device (MS Windows, OS/2, gtk+) can be used with different color models: Gray, RGB, CMYK only, or CMYK plus spot colors (separation). The display device, when using its CMYK plus spot color (separation) mode, also uses an equivalent CMYK color to simulate the appearance of the spot color. The tiffsep device creates output files for each separation (CMYK and any spot colors present). It also creates a composite CMYK file using an equivalent CMYK color to simulate the appearance of spot colors. The xcfcmyk device creates output files with spot colors placed in separate alpha channels. (The XCF file format does not currently directly support spot colors.)

Overprinting with spot colors is not allowed if the tint transform function is being used to convert spot colors. Thus if spot colors are used with overprinting, then the appearance of the result can differ between output devices. One result would be obtained with a CMYK only device and another would be obtained with a CMYK plus spot color device. In a worst case situation where a file has overprinting with both process (CMYK) and spot colors, it is possible to get three different appearances for the same input file using the tiff24nc (RGB), tiff32nc (CMYK), and tiffsep (CMYK plus spot colors) devices.

In Adobe Acrobat, viewing of the effects of overprinting is enabled by the 'Overprint Preview' item in the 'Advanced' menu. This feature is not available in the free Acrobat Reader. The free Acrobat Reader also uses the tint transform functions to convert spot colors to the appropriate alternate color space.

How Ghostscript finds files

When looking for initialization files (gs_*.ps, pdf_*.ps), font files, the Fontmap file, files named on the command line, and resource files, Ghostscript first tests whether the file name specifies an absolute path.

Testing a file name for an absolute path
System    Does the name ...
Unix   Begin with / ?
MS Windows   Have : as its second character, or begin with /, \, or //servername/share/ ?
VMS   Contain a node, device, or root specification?

If the test succeeds, Ghostscript tries to open the file using the name given. Otherwise it tries directories in this order:

  1. The current directory if enabled by the -P switch;
  2. The directories specified by -I switches in the command line, if any;
  3. The directories specified by the GS_LIB environment variable, if any;
  4. If built with COMPILE_INITS=1 (currently the default build) the files in the %rom%Resource/ and %rom%iccprofiles/ directories are built into the executable.
  5. The directories specified by the GS_LIB_DEFAULT macro (if any) in the makefile when this executable was built.

GS_LIB_DEFAULT, GS_LIB, and the -I parameter may specify either a single directory or a list of directories separated by a character appropriate for the operating system (":" on Unix systems, "," on VMS systems, and ";" on MS Windows systems). By default, Ghostscript no longer searches the current directory first but provides -P switch for a degree of backward compatibility.

Note that Ghostscript does not use this file searching algorithm for the run or file operators: for these operators, it simply opens the file with the name given. To run a file using the searching algorithm, use runlibfile instead of run.

Finding PostScript Level 2 resources

Adobe specifies that resources are installed in a single directory. Ghostscript instead maintains a list of resource directories, and uses an extended method for finding resource files.

The search for a resource file depends on whether the value of the system parameter GenericResourceDir specifies an absolute path. The user may set it as explained in Resource-related parameters.

If the user doesn't set the system parameter GenericResourceDir, or use the -sGenericResourceDir= command line option, Ghostscript creates a default value for it by looking on the directory paths explained in How Ghostscript finds files, excluding the current directory. The first path with Resource in it is used, including any prefix up to the path separator character following the string Resource. For example, when COMPILE_INITS=1 (the current default build), if the first path is %rom%Resource/Init/, then the GenericResourceDir systemparam will be set to %rom%Resource/ by default.

If the value of the system parameter GenericResourceDir is an absolute path (the default), Ghostscript assumes a single resource directory. It concatenates :

  1. The value of the system parameter GenericResourceDir;
  2. The name of the resource category (for instance, CMap);
  3. The name of the resource instance (for instance, Identity-H).

If the value of the system parameter GenericResourceDir is not an absolute path, Ghostscript assumes multiple resource directories. In this case it concatenates :

  1. A directory listed in the section How Ghostscript finds files, except the current directory;
  2. The value of the system parameter GenericResourceDir;
  3. The name of the resource category (for instance, CMap);
  4. The name of the resource instance (for instance, Identity-H)

Due to possible variety of the part 1, the first successful combination is used. For example, if the value of the system parameter GenericResourceDir is the string ../Resource/ (or its equivalent in the file path syntax of the underlying platform), Ghostscript searches for ../Resource/CMap/Identity-H from all directories listed in How Ghostscript finds files. So in this example, if the user on a Windows platform specifies the command line option -I.;../gs/lib;c:/gs8.50/lib, Ghostscript searches for ../gs/Resource/CMap/Identity-H and then for c:/gs8.50/Resource/CMap/Identity-H.

To get a proper platform dependent syntax Ghostscript inserts the value of the system parameter GenericResourcePathSep (initially "/" on Unix and Windows, ":" on MacOS, "." or "]" on OpenVMS). The string ../Resource is replaced with a platform dependent equivalent.

In the case of multiple resource directories, the default ResourceFileName procedure retrieves either a path to the first avaliable resource, or if the resource is not available it returns a path starting with GenericResourceDir. Consequently Postscript installers of Postscript resources will overwrite an existing resource or add a new one to the first resource directory.

To look up fonts, after exhausting the search method described in the next section, it concatenates together

  1. the value of the system parameter FontResourceDir (initially /Resource/Font/)
  2. the name of the resource font (for instance, Times-Roman)

Note that even although the system parameters are named "somethingDir", they are not just plain directory names: they have "/" on the end, so that they can be concatenated with the category name or font name.

Font lookup

Ghostscript has a slightly different way to find the file containing a font with a given name. This rule uses not only the search path defined by -I, GS_LIB, and GS_LIB_DEFAULT as described above, but also the directory that is the value of the FontResourceDir system parameter, and an additional list of directories that is the value of the GS_FONTPATH environment variable (or the value provided with the -sFONTPATH= switch, if present).

At startup time, Ghostscript reads in the Fontmap files in every directory on the search path (or in the list provided with the -sFONTMAP= switch, if present): these files are catalogs of fonts and the files that contain them. (See the documentation of fonts for details.) Then, when Ghostscript needs to find a font that isn't already loaded into memory, it goes through a series of steps.

  • First, it looks up the font name in the combined Fontmaps. If there is an entry for the desired font name, and the file named in the entry can be found in some directory on the general search path (defined by -I, GS_LIB, and GS_LIB_DEFAULT), and the file is loaded successfully, and loading it defines a font of the desired name, that is the end of the process.
  • If this process fails at any step, Ghostscript looks for a file whose name is the concatenation of the value of the FontResourceDir system parameter and the font name, with no extension. If such a file exists, can be loaded, and defines a font of the desired name, that again is the end. The value of FontResourceDir is normally the string /Resource/Font/, but it can be changed with the setsystemparams operator: see the PostScript Language Reference Manual for details.
  • If that fails, Ghostscript then looks for a file on the general search path whose name is the desired font name, with no extension. If such a file exists, can be loaded, and defines a font of the desired name, that again is the end.
  • If that too fails, Ghostscript looks at the GS_FONTPATH environment variable (or the value provided with the -sFONTPATH= switch, if present), which is also a list of directories. It goes to the first directory on the list, and it's descendants, looking for all files that appear to contain PostScript fonts (also Truetype fonts); it then adds all those files and fonts to the combined Fontmaps, and starts over.
  • If scanning the first FONTPATH directory doesn't produce a file that provides the desired font, it adds the next directory on the FONTPATH list, and so on until either the font is defined successfully or the list is exhausted.
  • Finally, if all else fails, it will try to find a substitute for the font from among the standard 35 fonts.

CID fonts (e.g. Chinese, Japanese and Korean) are found using a different method.

Differences between search path and font path
Search path     Font path
-I switch   -sFONTPATH= switch
GS_LIB and GS_LIB_DEFAULT environment variables   GS_FONTPATH environment variable
Consulted first   Consulted only if search path and FontResourceDir don't provide the file.
Font-name-to-file-name mapping given in Fontmap files; aliases are possible, and there need not be any relation between the font name in the Fontmap and the FontName in the file.   Font-name-to-file-name mapping is implicit – the FontName in the file is used. Aliases are not possible.
Only fonts and files named in Fontmap are used.   Every Type 1 font file in each directory is available; if TrueType fonts are supported (the ttfont.dev feature was included when the executable was built), they are also available.

If you are using one of the following types of computer, you may wish to set the environment variable GS_FONTPATH to the value indicated so that Ghostscript will automatically acquire all the installed Type 1 (and, if supported, TrueType) fonts (but see below for notes on systems marked with "*"):

Suggested GS_FONTPATH for different systems
     System type    GS_FONTPATH
    Digital Unix   /usr/lib/X11/fonts/Type1Adobe
    Ultrix   /usr/lib/DPS/outline/decwin
    HP-UX 9   /usr/lib/X11/fonts/type1.st/typefaces
    IBM AIX   /usr/lpp/DPS/fonts/outlines
/usr/lpp/X11/lib/X11/fonts/Type1
/usr/lpp/X11/lib/X11/fonts/Type1/DPS
    NeXT   /NextLibrary/Fonts/outline
*   SGI IRIX   /usr/lib/DPS/outline/base
/usr/lib/X11/fonts/Type1
    SunOS 4.x
(NeWSprint only)		   newsprint_2.5/SUNWsteNP/reloc/$BASEDIR/NeWSprint/
    small_openwin/lib/fonts
**   SunOS 4.x   /usr/openwin/lib/X11/fonts/Type1/outline
**   Solaris 2.x   /usr/openwin/lib/X11/fonts/Type1/outline
    VMS   SYS$COMMON:[SYSFONT.XDPS.OUTLINE]

* On SGI IRIX systems, you must use Fontmap.SGI in place of Fontmap or Fontmap.GS, because otherwise the entries in Fontmap will take precedence over the fonts in the FONTPATH directories.

** On Solaris systems simply setting GS_FONTPATH or using -sFONTPATH= may not work, because for some reason some versions of Ghostscript can't seem to find any of the Type1 fonts in /usr/openwin/lib/X11/fonts/Type1/outline. (It says: "15 files, 15 scanned, 0 new fonts". We think this problem has been fixed in Ghostscript version 6.0, but we aren't sure because we've never been able to reproduce it.) See Fontmap.Sol instead. Also, on Solaris 2.x it's probably not worth your while to add Sun's fonts to your font path and Fontmap. The fonts Sun distributes on Solaris 2.x in the directories

/usr/openwin/lib/X11/fonts/Type1
/usr/openwin/lib/X11/fonts/Type1/outline

are already represented among the ones distributed as part of Ghostscript; and on some test files, Sun's fonts have been shown to cause incorrect displays with Ghostscript.

These paths may not be exactly right for your installation; if the indicated directory doesn't contain files whose names are familiar font names like Courier and Helvetica, you may wish to ask your system administrator where to find these fonts.

Adobe Acrobat comes with a set of fourteen Type 1 fonts, on Unix typically in a directory called .../Acrobat3/Fonts. There is no particular reason to use these instead of the corresponding fonts in the Ghostscript distribution (which are of just as good quality), except to save about a megabyte of disk space, but the installation documentation explains how to do it on Unix.

CID fonts

CID fonts are PostScript resources containing a large number of glyphs (e.g. glyphs for Far East languages, Chinese, Japanese and Korean). Please refer to the PostScript Language Reference, third edition, for details.

CID font resources are a different kind of PostScript resource from fonts. In particular, they cannot be used as regular fonts. CID font resources must first be combined with a CMap resource, which defines specific codes for glyphs, before it can be used as a font. This allows the reuse of a collection of glyphs with different encodings.

The simplest method to request a font composed of a CID font resource and a CMap resource in a PostScript document is

/CIDFont-CMap findfont
where CIDFont is a name of any CID font resource, and CMap is a name of a CMap resource designed for the same character collection. The interpreter will compose the font automatically from the specified CID font and CMap resources. Another method is possible using the composefont operator.

CID fonts must be placed in the /Resource/CIDFont/ directory. They are not found using Font lookup on the search path or font path.

CID font substitution

Automatic CIDFont Substitution

In general, it is highly recommended that CIDFonts used in the creation of PDF jobs should be embedded or available to Ghostscript as CIDFont resources, this ensures that the character set, and typeface style are as intended by the author.

In cases where the original CIDFont is not available, the next best option is to provide Ghostscript with a mapping to a suitable alternative CIDFont - see below for details on how this is achieved. However, Ghostscript does provide the ability to use a "fall back" CIDFont substitute. As shipped, this uses the DroidSansFallback.ttf font. This font contains a large number of glyphs covering several languages, but it is not comprehensive. There is, therefore, a chance that glyphs may be wrong, or missing in the output when this fallback is used.

Internally, the font is referenced as CIDFont resource called CIDFallBack, thus a different fallback from DroidSansFallback.ttf can be specified adding a mapping to your cidfmap file (see below for details) to map the name "CIDFallBack" as you prefer. For CIDFallBack the mapping must be a TrueType font or TrueType collection, it cannot be a Postscript CIDFont file.

As with any font containing large numbers of glyphs, DroidSansFallback.ttf is quite large (~3.5Mb at the of writing). If this is space you cannot afford in your use of Ghostscript, you can simply delete the file from: Resource/CIDFSubst/DroidSansFallback.ttf. The build system will cope with the file being removed, and the initialization code will avoid adding the internal fall back mapping if the file is missing.

If DroidSansFallback.ttf is removed, and no other CIDFallBack mapping is supplied, the final "fall back" is to use a "dumb" bullet CIDFont, called ArtifexBullet. As the name suggests, this will result in all the glyphs from a missing CIDFont being replaced with a simple bullet point.

This type of generic fall back CIDFont substitution can be very useful for viewing and proofing jobs, but may not be appropriate for a "production" workflow, where it is expected that only the original font should be used. For this situation, you can supply Ghostscript with the command line option: -dPDFNOCIDFALLBACK. By combining -dPDFNOCIDFALLBACK with -dPDFSTOPONERROR a production workflow can force a PDF with missing CIDFonts to error, and avoid realising a CIDFont was missing only after printing.

The directory in which the fallback TrueType font or collection can be specified by the command line parameter -sCIDFSubstPath="path/to/TTF", or with the environment variable CIDFSUBSTPATH. The file name of the substitute TrueType font can be specified using the command line parameter -sCIDFSubstFont="TTF file name" or the environment variable CIDFSUBSTFONT.

Explicit CIDFont Substitution

Substitution of CID font resources is controlled, by default, by the Ghostscript configuration file Resource/Init/cidfmap, which defines a CID font resource map.

The file forms a table of records, each of which should use one of three formats, explained below. Users may modify Resource/Init/cidfmap to configure Ghostscript for a specific need. Note that the default Ghostscript build includes such configuration and resource files in a rom file system built into the executable. So, to ensure your changes have an effect, you should do one of the following: rebuild the executable; use the "-I" command line option to add the directory containing your modified file to Ghostscript's search path; or, finally, build Ghostscript to use disk based resources.

Format 1

To substitute a CID font resource with another CID font resource, add a record like this :

/Substituted /Original ;

where Substituted is a name of CID font resource being used by a document, and Original is a name of an available CID font resource. Please pay attention that both them must be designed for same character collection. In other words, you cannot substitute a Japanese CID font resource with a Korean CID font resource, etc. CMap resource names must not appear in lib/cidfmap. The trailing semicolon and the space before it are both required.

Format 2

To substitute (emulate) a CID font resource with a TrueType font file, add a record like this :

/Substituted << keys&values >> ;

Where keys&values are explained in the table below.

Key Type Description
/Path string A path to a TrueType font file. This must be an absolute path. If using -dSAFER, the directory containing the font file must be on one of the permitted paths.
/FileType name Must be /TrueType.
/SubfontID integer (optional) Index of the font in font collection, such as TTC. This is ignored if Path doesn't specify a collection. The first font in a collection is 0. Default value is 0.
/CSI array of 2 or 3 elements (required) Information for building CIDSystemInfo.

If the array consists of 2 elements, the first element is a string, which specifies Ordering; the second element is a number, which specifies Supplement.

If the array consists of 3 elements, the first element is a string, which specifies Registry; the second element is a string, which specifies Ordering; the third element is a number, which specifies Supplement.

Currently only CIDFontType 2 can be emulated with a TrueType font. The TrueType font must contain enough characters to cover an Adobe character collection, which is specified in Ordering and used in documents.

Format 3

To point Ghostscript at a specific CIDFont file outside it's "normal" resource search path :

/CIDName (path/to/cid/font/file) ;

where CIDName is a name of CID font resource being used by a document, and "path/to/cid/font/file" is the path to the Postscript CIDFont file, including the file name. NOTE: the CIDFont file, when executed by the Postscript interpreter, must result in a CIDFont resource being defined whose CIDFontName matches the "CIDName" key for the current record. I.E. an entry with the key /PingHei-Bold must reference a file which creates a CIDFont resource called "PingHei-Bold". To substitute a file based CIDFont for a differently named CIDFont, use formats 1 and 3 in combination (the order of the entries is not important).

The trailing semicolon and the space before it are both required.

NOTE: Environment Variables

It is also possible to influence the path using standard, or your own environment variables, using the custom Postscript operator getenv. Said operator takes a string parameter on the stack which is the environment variable to interrogate, and returns either a string, containing the value of the environment variable, and boolean true to indicate success, or just a boolean false to indicate failure. See below for an example of its use.

Examples :

Format 1:
/Ryumin-Medium /ShinGo-Bold ;
/Ryumin-Light /MS-Mincho ;
Format 2:
/Batang << /FileType /TrueType /Path (C:/WINDOWS/fonts/batang.ttc) /SubfontID 0 /CSI [(Korea1) 3] >> ;
/Gulim << /FileType /TrueType /Path (C:/WINDOWS/fonts/gulim.ttc) /SubfontID 0 /CSI [(Korea1) 3] >> ;
/Dotum << /FileType /TrueType /Path (C:/WINDOWS/fonts/gulim.ttc) /SubfontID 2 /CSI [(Korea1) 3] >> ;

Format 2 & environment variable:
/SimHei << /FileType /TrueType /Path (windir) getenv not {(c:/windows)}if (/fonts/simhei.ttf) concatstrings /SubfontID 0 /CSI [(GB1) 2] >> ;
Format 1 & 2
/SimSun << /FileType /TrueType /Path (C:/WINDOWS/fonts/simsun.ttc) /SubfontID 0 /CSI [(GB1) 2] >> ;
/SimHei << /FileType /TrueType /Path (C:/WINDOWS/fonts/simhei.ttf) /SubfontID 0 /CSI [(GB1) 2] >> ;
/STSong-Light /SimSun ;
/STHeiti-Regular /SimHei ;
Format 3:
/PMingLiU (/usr/local/share/font/cidfont/PMingLiU.cid) ;
Format 1 & 3
/Ryumin-Light /PMingLiU ;
/PMingLiU (/usr/local/share/font/cidfont/PMingLiU.cid) ;

The win32 installer of recent version of ghostscript has a checkbox for "Use Windows TrueType fonts for Chinese, Japanese and Korean" to optionally update lib/cidfmap with the common CJK fonts provided by Microsoft products. The script can also be run separately (e.g. against a network drive with windows CJK fonts):

gswin32c -q -dBATCH -sFONTDIR=c:/windows/fonts -sCIDFMAP=lib/cidfmap lib/mkcidfm.ps

Note that the font file path uses Postscript syntax. Because of this, backslashes in the paths must be represented as a double backslash.

This can complicate substitutions for fonts with non-Roman names. For example, if a PDF file asks for a font with the name /#82l#82r#83S#83V#83b#83N. This cannot be used directly in a cidfmap file because the #xx notation in names is a PDF-only encoding. Instead, try something like:

<82C68272835383568362834E>cvn << /Path (C:/WINDOWS/Fonts/msmincho.ttc) /FileType /TrueType /SubfontID 0 /CSI [(Japan1) 3] >> ;

Where <82C68272835383568362834E> is the same byte sequence converted to a hex string. This lets you specify a name using any sequence of bytes through the encodings available for Postscript strings.

Note that loading truetype fonts directly from /Resources/CIDFont is no longer supported. There is no reliable way to generate a character ordering for truetype fonts. The 7.0x versions of Ghostscript supported this by assuming a Japanese character ordering. This is replaced in the 8.0x and later releases with the more general cidfmap mechanism.

The PDF specification requires CID font files to be embedded, however some documents omit them. As a workaround the PDF interpreter applies an additional substitution method when a requested CID font resource is not embedded and it is not available. It takes values of the keys Registry and Ordering from the CIDFontSystem dictionary, and concatenates them with a dash inserted. For example, if a PDF CID font resource specifies

/CIDSystemInfo << /Registry (Adobe) /Ordering (CNS1) /Supplement 1 >>
the generated subsitituite name is Adobe-CNS1. The latter may look some confusing for a font name, but we keep it for compatibility with older Ghostscript versions, which do so due to a historical reason. Add a proper record to lib/cidfmap to provide it.

Please note that when a PDF font resource specifies

/Registry (Adobe) /Ordering (Identity)
there is no way to determine the language properly. If the CID font file is not embedded, the Adobe-Identity record depends on the document and a correct record isn't possible when a document refers to multiple Far East languages. In the latter case add individual records for specific CID font names used in the document.

Consequently, if you want to handle any PDF document with non-embedded CID fonts (which isn't a correct PDF), you need to create a suitable lib/cidfmap by hand, possibly a specific one for each document.

Using Unicode True Type fonts

Ghostscript can make use of Truetype fonts with a Unicode character set. To do so, you should generate a (NOTE: non-standard!) Postscript or PDF job where the relevant text is encoded as UTF-16. Ghostscript may be used for converting such jobs to other formats (Postscript, PDF, PXL etc). The resulting output will be compliant with the spec (unlike the input).

To render an UTF-16 encoded text, one must do the following :

  • Provide a True Type font with Unicode Encoding. It must have a cmap table with platformID equals to 3 (Windows), and SpecificID eqials to 1 (Unicode).
  • Describe the font in Resource/Init/cidfmap with special values for the CSI key : [(Artifex) (Unicode) 0].
  • In the PS or PDF job combine the font with one of CMap Identity-UTF16-H (for the horizontal writing mode) or Identity-UTF16-V (for the vertical writing mode). Those CMaps are distributed with Ghostscript in Resource/CMap.

Please note that /Registry (Adobe) /Ordering (Identity) won't properly work for Unicode documents, especially for the searchability feature (see CID font substitution).

Temporary files

Where Ghostscript puts temporary files
Platform     Filename     Location
MS Windows and OpenVMS   _temp_XX.XXX   Current directory
OS/2   gsXXXXXX   Current directory
Unix   gs_XXXXX   /tmp

You can change in which directory Ghostscript creates temporary files by setting the TMPDIR or TEMP environment variable to the name of the directory you want used. Ghostscript currently doesn't do a very good job of deleting temporary files if it exits because of an error; you may have to delete them manually from time to time.

Notes on specific platforms

Word size (32 or 64 bits)

The original PostScript language specification, while not stating a specific word sise, defines 'typical' limits which make it clear that it was intended to run as a 32-bit environment. Ghostscript was originally coded that way, and the heritage remains within the code base.

Because the Ghostscript PDF interpreter is currently written in PostScript, it proved necessary to add support for 64-bit integers so that we could process PDF files which exceed 2GB in size. This is the only real purpose in adding support for large integers, however since that time, we have made some efforts to allow for the use of 64-bit words; in particular the use of integers, but also lifting the 64K limit on strings and arrays, among other areas.

However this is, obviously, dependent on the operating system and compiler support available. Not all builds of Ghostscript will support 64-bit integers, though some 32-bit builds (eg Windows) will.

Even when the build supports 64-bit words, you should be aware that there are areas of Ghostscript which do not support 64-bit values. Sometimes these are dependent on the build and other times they are inherent in the architecture of Ghostscript (the graphics library does not support 64-bit co-ordinates in device space for example, and most likely never will).

Note that the extended support for 64-bit word size can be disabled by executing 'true .setcpsimode', This is important for checking the output of the Quality Logic test suite (and possibly other test suites) as the tests make assumptions about the sizes of integers (amongst other things). You can run /ghostpdl/Resource/Init/gs_cet.ps to change Ghostscript's behaviour so that it matches the observed behaviour of Adobe CPSI interpreters.

Unix

The Ghostscript distribution includes some Unix shell scripts to use with Ghostscript in different environments. These are all user-contributed code, so if you have questions, please contact the user identified in the file, not Artifex Software.

pv.sh
Preview a specified page of a dvi file in an X window
sysvlp.sh
System V 3.2 lp interface for parallel printer
pj-gs.sh
Printing on an H-P PaintJet under HP-UX
unix-lpr.sh
Queue filter for lpr under Unix; its documentation is intended for system administrators
lprsetup.sh
Setup for unix-lpr.sh

VMS

  • To be able to specify switches and file names when invoking the interpreter, define gs as a foreign command:
    • $ gs == "$disk:[directory]gs.exe"

    where the "disk" and "directory" specify where the Ghostscript executable is located. For instance,

    $ gs == "$dua1:[ghostscript]gs.exe"
  • On VMS systems, the last character of each "directory" name indicates what sort of entity the "directory" refers to. If the "directory" name ends with a colon ":", it is taken to refer to a logical device, for instance
    • $ define ghostscript_device dua1:[ghostscript_510]
    $ define gs_lib ghostscript_device:

    If the "directory" name ends with a closing square bracket "]", it is taken to refer to a real directory, for instance

    $ define gs_lib dua1:[ghostscript]
  • Defining the logical GS_LIB
    • $ define gs_lib disk:[directory]

    allows Ghostscript to find its initialization files in the Ghostscript directory even if that's not where the executable resides.

  • Although VMS DCL itself converts unquoted parameters to upper case, C programs such as Ghostscript receive their parameters through the C runtime library, which forces all unquoted command-line parameters to lower case. That is, with the command
    • $ gs -Isys$login:

    Ghostscript sees the switch as -isys$login, which doesn't work. To preserve the case of switches, quote them like this:

    $ gs "-Isys$login:"
  • If you write printer output to a file with -sOutputFile= and then want to print the file later, use "PRINT/PASSALL".
  • PDF files (or PostScript files that use the setfileposition operator) must be "stream LF" type files to work properly on VMS systems. (Note: This definitely matters if Ghostscript was compiled with DEC C; we are not sure of the situation if you use gcc.) Because of this, if you transfer files by FTP, you probably need to do one of these two things after the transfer:
    1. If the FTP transfer was in text (ASCII) mode:
      2. $ convert/fdl=streamlf.fdl input-file output-file

      where the contents of the file STREAMLF.FDL are

      FILE
        ORGANIZATION            sequential

RECORD
        BLOCK_SPAN              yes
        CARRIAGE_CONTROL        carriage_return
        FORMAT                  stream_lf
    2. If the FTP transfer was in binary mode:
      3. $ set file/attribute=(rfm:stmlf)

Using X Windows on VMS

If you are using on an X Windows display, you can set it up with the node name and network transport, for instance

$ set display/create/node="doof.city.com"/transport=tcpip

and then run Ghostscript by typing gs at the command line.

MS Windows

The name of the Ghostscript command line executable on MS Windows is gswin32c/gswin64c so use this instead of the plain 'gs' in the quickstart examples.

To run the batch files in the ghostscript lib directory, you must add gs\bin and gs\lib to the PATH, where gs is the top-level Ghostscript directory.

When passing options to ghostcript through a batch file wrapper such as ps2pdf.bat you need to substitute '#' for '=' as the separator between options and their arguments. For example:

ps2pdf -sPAPERSIZE#a4 file.ps file.pdf

Ghostscript treats '#' the same internally, and the '=' is mangled by the command shell.

There is also an older version for MS Windows called just gswin32 that provides its own window for the interactive postscript prompt. The executable gswin32c/gswin64c is usually the better option since it uses the native command prompt window.

For printer devices, the default output is the default printer. This can be modified as follows.

-sOutputFile="%printer%printer name"
Output to the named printer. If your printer is named "HP DeskJet 500" then you would use -sOutputFile="%printer%HP DeskJet 500".

MS-DOS

Note: Ghostscript is no longer supported on MS-DOS.

Invoking Ghostscript from the command prompt in Windows is supported by the Windows executable described above.

X Windows

Ghostscript looks for the following resources under the program name ghostscript and class name Ghostscript; the ones marked "**" are calculated from display metrics:

X Windows resources
Name    Class    Default
background   Background   white
foreground   Foreground   black
borderColor   BorderColor   black
borderWidth   BorderWidth   1
geometry   Geometry   NULL
xResolution   Resolution   **
yResolution   Resolution   **
useExternalFonts   UseExternalFonts   true
useScalableFonts   UseScalableFonts   true
logExternalFonts   LogExternalFonts   false
externalFontTolerance   ExternalFontTolerance   10.0
palette   Palette   Color
maxGrayRamp   MaxGrayRamp   128
maxRGBRamp   MaxRGBRamp   5
maxDynamicColors   MaxDynamicColors   256
useBackingPixmap   UseBackingPixmap   true
useXPutImage   UseXPutImage   true
useXSetTile   UseXSetTile   true

X resources

  • To set X resources, put them in a file (such as ~/.Xdefaults on Unix) in a form like this:
    • Ghostscript*geometry:  595x842-0+0
    Ghostscript*xResolution: 72
    Ghostscript*yResolution: 72

    Then merge these resources into the X server's resource database:

    xrdb -merge ~/.Xdefaults
  • Ghostscript doesn't look at the default system background and foreground colors; if you want to change the background or foreground color, you must set them explicitly for Ghostscript. This is a deliberate choice, so that PostScript documents will display correctly by default -- with white as white and black as black -- even if text windows use other colors.
  • The geometry resource affects only window placement.
  • Resolution is expressed in pixels per inch (1 inch = 25.4mm).
  • The font tolerance gives the largest acceptable difference in height of the screen font, expressed as a percentage of the height of the desired font.
  • The palette resource can be used to restrict Ghostscript to using a grayscale or monochrome palette.
  • maxRGBRamp and maxGrayRamp control the maximum number of colors that ghostscript allocates ahead of time for the dither cube (ramp). Ghostscript never preallocates more than half the cells in a colormap. maxDynamicColors controls the maximum number of colors that Ghostscript will allocate dynamically in the colormap.

Working around bugs in X servers

The "use..." resources exist primarily to work around bugs in X servers.

  • Old versions of DEC's X server (DECwindows) have bugs that require setting useXPutImage or useXSetTile to false.
  • Some servers do not implement backing pixmaps properly, or do not have enough memory for them. If you get strange behavior or "out of memory" messages, try setting useBackingPixmap to false.
  • Some servers do not implement tiling properly. This appears as broad bands of color where dither patterns should appear. If this happens, try setting useXSetTile to false.
  • Some servers do not implement bitmap or pixmap displaying properly. This may appear as white or black rectangles where characters should appear; or characters may appear in "inverse video" (for instance, white on a black rectangle rather than black on white). If this happens, try setting useXPutImage to false.

X device parameters

In addition to the device parameters recognized by all devices, Ghostscript's X driver provides parameters to adjust its performance. Users will rarely need to modify these. Note that these are parameters to be set with the -d switch in the command line (e.g., -dMaxBitmap=10000000), not resources to be defined in the ~/.Xdefaults file.

AlwaysUpdate <boolean>
If true, the driver updates the screen after each primitive drawing operation; if false (the default), the driver uses an intelligent buffered updating algorithm.
MaxBitmap <integer>
If the amount of memory required to hold the pixmap for the window is no more than the value of MaxBitmap, the driver will draw to a pixmap in Ghostscript's address space (called a "client-side pixmap") and will copy it to the screen from time to time; if the amount of memory required for the pixmap exceeds the value of MaxBitmap, the driver will draw to a server pixmap. Using a client-side pixmap usually provides better performance -- for bitmap images, possibly much better performance -- but since it may require quite a lot of RAM (e.g., about 2.2 Mb for a 24-bit 1024x768 window), the default value of MaxBitmap is 0.
MaxTempPixmap, MaxTempImage <integer>
These control various aspects of the driver's buffering behavior. For details, please consult the source file gdevx.h.

SCO Unix

Because of bugs in the SCO Unix kernel, Ghostscript will not work if you select direct screen output and also allow it to write messages on the console. If you are using direct screen output, redirect Ghostscript's terminal output to a file.

Command line options

Unless otherwise noted, these switches can be used on all platforms.

General switches

Input control

@filename
Causes Ghostscript to read filename and treat its contents the same as the command line. (This was intended primarily for getting around DOS's 128-character limit on the length of a command line.) Switches or file names in the file may be separated by any amount of white space (space, tab, line break); there is no limit on the size of the file.
-- filename arg1 ...
-+ filename arg1 ...
Takes the next argument as a file name as usual, but takes all remaining arguments (even if they have the syntactic form of switches) and defines the name ARGUMENTS in userdict (not systemdict) as an array of those strings, before running the file. When Ghostscript finishes executing the file, it exits back to the shell.
-@ filename arg1 ...
Does the same thing as -- and -+, but expands @filename arguments.
-
-_
These are not really switches: they tell Ghostscript to read from standard input, which is coming from a file or a pipe, with or without buffering. On some systems, Ghostscript may read the input one character at a time, which is useful for programs such as ghostview that generate input for Ghostscript dynamically and watch for some response, but can slow processing. If performance is significantly slower than with a named file, try '-_' which always reads the input in blocks. However, '-' is equivalent on most systems.
-c token ...
-c string ...
Interprets arguments as PostScript code up to the next argument that begins with "-" followed by a non-digit, or with "@". For example, if the file quit.ps contains just the word "quit", then -c quit on the command line is equivalent to quit.ps there. Each argument must be valid PostScript, either individual tokens as defined by the token operator, or a string containing valid PostScript.

Because Ghostscript must initialize the PostScript environment before executing the commands specified by this option it should be specified after other setup options. Specifically this option 'bind's all operations and sets the systemdict to readonly.

-f
Interprets following non-switch arguments as file names to be executed using the normal run command. Since this is the default behavior, -f is useful only for terminating the list of tokens for the -c switch.
-ffilename
Execute the given file, even if its name begins with a "-" or "@".

File searching

Note that by "library files" here we mean all the files identified using the search rule under "How Ghostscript finds files" above: Ghostscript's own initialization files, fonts, and files named on the command line.

-Idirectories
-I directories
Adds the designated list of directories at the head of the search path for library files.
-P
Makes Ghostscript look first in the current directory for library files.
-P-
Makes Ghostscript not look first in the current directory for library files (unless, of course, the first explicitly supplied directory is "."). This is now the default.

Setting parameters

-Dname
-dname
Define a name in systemdict with value=true.
-Dname=token
-dname=token
Define a name in systemdict with the given value. The value must be a valid PostScript token (as defined by the token operator). If the token is a non-literal name, it must be true, false, or null. It is recommeded that this is used only for simple values -- use -c (above) for complex values such as procedures, arrays or dictionaries.
Note that these values are defined before other names in systemdict, so any name that that conflicts with one usually in systemdict will be replaced by the normal definition during the interpreter initialization.
-Sname=string
-sname=string
Define a name in systemdict with a given string as value. This is different from -d. For example, -dXYZ=35 on the command line is equivalent to the program fragment
/XYZ 35 def

whereas -sXYZ=35 is equivalent to

/XYZ (35) def
-pname=string
Define a name in systemdict with the parsed version of the given string as value. The string takes a parameter definition in (something very close to) postscript format. This allows more complex structures to be passed in than is possible with -d or -s. For example:
-pFoo="<< /Bar[1 2 3]/Baz 0.1 /Whizz (string) /Bang <0123> >>"

This means that -p can do the job of both -d and -s. For example:

-dDownScaleFactor=3

can be equivalently performed by

-pDownScaleFactor=3
and
-sPAPERSIZE=letter

can be equivalently performed by

-pPAPERSIZE="(letter)"

Note, that there are some 'special' values that should be set using -s, not -p, such as DEVICE and DefaultGrayProfile. Broadly, only use -p if you cannot set what you want using -s or -d.

Also, internally, after setting an parameter with -p we perform an initgraphics operation. This is required to allow changes in parameters such as HWResolution to take effect. This means that attempting to use -p other than at the start of a page is liable to give unexpected results.

-uname
Un-define a name, cancelling -d or -s.

Note that the initialization file gs_init.ps makes systemdict read-only, so the values of names defined with -D, -d, -S, and -s cannot be changed -- although, of course, they can be superseded by definitions in userdict or other dictionaries. However, device parameters set this way (PageSize, Margins, etc.) are not read-only, and can be changed by code in PostScript files.

-gnumber1xnumber2
Equivalent to -dDEVICEWIDTH=number1 and -dDEVICEHEIGHT=number2, specifying the device width and height in pixels for the benefit of devices such as X11 windows and VESA displays that require (or allow) you to specify width and height. Note that this causes documents of other sizes to be clipped, not scaled: see -dFIXEDMEDIA below.
-rnumber (same as -rnumberxnumber)
-rnumber1xnumber2
Equivalent to -dDEVICEXRESOLUTION=number1 and -dDEVICEYRESOLUTION=number2, specifying the device horizontal and vertical resolution in pixels per inch for the benefit of devices such as printers that support multiple X and Y resolutions.

Suppress messages

-q
Quiet startup: suppress normal startup messages, and also do the equivalent of -dQUIET.

Parameter switches (-d and -s)

As noted above, -d and -s define initial values for PostScript names. Some of these names are parameters that control the interpreter or the graphics engine. You can also use -d or -s to define a value for any device parameter of the initial device (the one defined with -sDEVICE=, or the default device if this switch is not used). For example, since the ppmraw device has a numeric GrayValues parameter that controls the number of bits per component, -sDEVICE=ppmraw -dGrayValues=16 will make this the default device and set the number of bits per component to 4 (log2(16)).

Rendering parameters

-dCOLORSCREEN
-dCOLORSCREEN=0
-dCOLORSCREEN=false
On high-resolution devices (at least 150 dpi resolution, or -dDITHERPPI specified), -dCOLORSCREEN forces the use of separate halftone screens with different angles for CMYK or RGB if halftones are needed (this produces the best-quality output); -dCOLORSCREEN=0 uses separate screens with the same frequency and angle; -dCOLORSCREEN=false forces the use of a single binary screen. The default if COLORSCREEN is not specified is to use separate screens with different angles if the device has fewer than 5 bits per color, and a single binary screen (which is never actually used under normal circumstances) on all other devices.
-dDITHERPPI=lpi
Forces all devices to be considered high-resolution, and forces use of a halftone screen or screens with lpi lines per inch, disregarding the actual device resolution. Reasonable values for lpi are N/5 to N/20, where N is the resolution in dots per inch.
-dInterpolateControl=control_value
This allows control of the image interpolation.

By default InterpolateControl is 1 and the image rendering for images that have /Interpolate true are interpolated to the full device resolution. Otherwise, images are rendered using the nearest neighbour scaling (Bresenham's line algorithm through the image, plotting the closest texture coord at each pixel). When downscaling this results in some source pixels not appearing at all in the destination. When upscaling, each source pixels will cover at least one destination pixel.

When the control_value is 0 no interpolation is performed, whether or not the file has images with /Interpolate true.

When the control_value is greater than 1 interpolation is performed for images with /Interpolate true as long as the image scaling factor on either axis is larger than the control_value. Also, the interpolation only produces images that have (device resolution / control_value) maximum resolution rather than full device resolution. This allows for a performance vs. quality tradeoff since the number of pixels produced by the interpolation will be a fraction of the interpolated pixels at full device resolution. Every source pixel will contribute partially to the destination pixels.

When the InterpolateControl control_value is less than 0 interpolation is forced as if all images have /Interpolate true, and the interpolation is controlled by the absolute value of the control_value as described above. Thus, -dInterpolateControl=-1 forces all images to be interpolated at full device resolution.

Computationally, image interpolation is much more demanding than without interpolation (lots of floating point muliplies and adds for every output pixel vs simple integer additions, subtractions, and shifts).

In all but special cases image interpolation uses a Mitchell filter function to scale the contributions for each output pixel. When upscaling, every output pixel ends up being the weighted sum of 16 input pixels, When downscaling more source pixels will contribute to the interpolated pixels. Every source pixel has some effect on the output pixels.

-dDOINTERPOLATE
This option still works, but is deprecated, and is the equivalent of -dInterpolateControl=-1.
-dNOINTERPOLATE
This option still works, but is deprecated and is the equivalent of -dInterpolateControl=0
-dTextAlphaBits=n
-dGraphicsAlphaBits=n
These options control the use of subsample antialiasing. Their use is highly recommended for producing high quality rasterizations. The subsampling box size n should be 4 for optimum output, but smaller values can be used for faster rendering. Antialiasing is enabled separately for text and graphics content. Allowed values are 1, 2 or 4.

Note that because of the way antialiasing