deb-substvars(5) — Linux manual page


deb-substvars(5)               dpkg suite               deb-substvars(5)

NAME         top

       deb-substvars - Debian source substitution variables

SYNOPSIS         top

       debian/substvars, debian/binary-package.substvars, variables

DESCRIPTION         top

       Before dpkg-source, dpkg-gencontrol and dpkg-genchanges write
       their control information (to the source control file .dsc for
       dpkg-source and to standard output for dpkg-gencontrol and dpkg-
       genchanges) they perform some variable substitutions on the
       output file.

   Variable Syntax
       A variable substitution has the form ${variable-name}.  Variable
       names consist of alphanumerics (a-zA-Z0-9), hyphens (-) and
       colons (:) and start with an alphanumeric, and are case-
       sensitive, even though they might refer to other entities which
       are case-preserving.  Variable substitutions are performed
       repeatedly until none are left; the full text of the field after
       the substitution is rescanned to look for more substitutions.

   File Syntax
       Substitution variables can be specified in a file.  These files
       consist of lines of the form name=value or name?=value.  The =
       operator assigns a normal substitution variable, while the ?=
       operator (since dpkg 1.21.8) assigns an optional substitution
       variable which will emit no warnings even if unused.  Trailing
       whitespace on each line, blank lines, and lines starting with a #
       symbol (comments) are ignored.

       Variables can be set using the -V common option.  They can be
       also specified in the file debian/substvars (or whatever other
       file is specified using the -T common option).

       After all the substitutions have been done each occurrence of the
       string ${} (which is not an actual substitution variable) is
       replaced with a $ sign.  This can be used as an escape sequence
       such as ${}{VARIABLE} which will end up as ${VARIABLE} on the

       If a variable is referred to but not defined it generates a
       warning and an empty value is assumed.

       While variable substitution is done on all control fields, some
       of those fields are used and needed during the build when the
       substitution did not yet occur. That's why you can't use
       variables in the Package, Source and Architecture fields.

       Variable substitution happens on the content of the fields after
       they have been parsed, thus if you want a variable to expand over
       multiple lines you do not have to include a space after the
       newline. This is done implicitly when the field is output. For
       example, if the variable ${Description} is set to "foo is
       bar.${Newline}foo is great." and if you have the following field:

        Description: foo application
         More text.

       It will result in:

        Description: foo application
         foo is bar.
         foo is great.
         More text.

   Built-in Variable
       Additionally, the following standard variables are always

           The current host architecture (i.e. the architecture the
           package is being built for, the equivalent of DEB_HOST_ARCH).

           The current vendor name (since dpkg 1.20.0).  This value
           comes from the Vendor field for the current vendor's origin
           file, as dpkg-vendor(1) would retrieve it.

           The current vendor ID (since dpkg 1.20.0).  This is just the
           lowercase variant of vendor:Name.

           The source package version (since dpkg 1.13.19).

           The upstream source package version, including the Debian
           version epoch if any (since dpkg 1.13.19).

           The binary package version (which may differ from
           source:Version in a binNMU for example; since dpkg 1.13.19).

           The source package version (from the changelog file). This
           variable is now obsolete and emits an error when used as its
           meaning is different from its function, please use the
           source:Version or binary:Version as appropriate.

           The source package synopsis, extracted from the source stanza
           Description field, if it exists (since dpkg 1.19.0).

           The source package extended description, extracted from the
           source stanza Description field, if it exists (since dpkg

           The approximate total size of the package's installed files.
           This value is copied into the corresponding control file
           field; setting it will modify the value of that field. If
           this variable is not set dpkg-gencontrol will compute the
           default value by accumulating the size of each regular file
           and symlink rounded to 1 KiB used units, and a baseline of 1
           KiB for any other filesystem object type.  With hardlinks
           only being counted once as a regular file.

           Note: Take into account that this can only ever be an
           approximation, as the actual size used on the installed
           system will depend greatly on the filesystem used and its
           parameters, which might end up using either more or less
           space than the specified in this field.

           Additional disk space used when the package is installed. If
           this variable is set its value is added to that of the
           Installed-Size variable (whether set explicitly or using the
           default value) before it is copied into the Installed-Size
           control file field.

           The value of the source stanza field field-name (which must
           be given in the canonical capitalization; since dpkg
           1.18.11).  Setting these variables has no effect other than
           on places where they are expanded explicitly.  These
           variables are only available when generating binary control

           The value of the output field field-name (which must be given
           in the canonical capitalization). Setting these variables has
           no effect other than on places where they are expanded

           The .changes file format version generated by this version of
           the source packaging scripts. If you set this variable the
           contents of the Format field in the .changes file will change

       Newline, Space, Tab
           These variables each hold the corresponding character.

           Variable settings with names of this form are generated by

           The upstream version of dpkg (since dpkg 1.13.19).

           The full version of dpkg (since dpkg 1.13.19).

FILES         top

           List of substitution variables and values.

SEE ALSO         top

       dpkg(1), dpkg-vendor(1), dpkg-genchanges(1), dpkg-gencontrol(1),
       dpkg-shlibdeps(1), dpkg-source(1).

COLOPHON         top

       This page is part of the dpkg (Debian Package Manager) project.
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       for this manual page, see
       ⟨⟩.  This
       page was obtained from the project's upstream Git repository ⟨git
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1.22.0-52-g1af0                2023-08-30               deb-substvars(5)

Pages that refer to this page: dpkg-genchanges(1)dpkg-gencontrol(1)dpkg-shlibdeps(1)dpkg-source(1)deb-control(5)