NAME

       deb-substvars - Debian source substitution variables

SYNOPSIS

       substvars

DESCRIPTION

       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.

       A variable  substitution  has  the  form  ${variable-name}.   Variable  names  consist  of
       alphanumerics,  hyphens  and colons and start with an alphanumeric. 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.

       After all the substitutions have been done each occurrence of the string ${} (which is not
       a legal substitution) is replaced with a $ sign.

       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
         ${Description}
         .
         More text.

       It will result in:

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

       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 option). This file
       consists of lines of the form name=value.  Trailing whitespace on each line, blank  lines,
       and lines starting with a # symbol (comments) are ignored.

       Additionally, the following standard variables are available:

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

       source:Version
              The source package version (since dpkg 1.13.19).

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

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

       Source-Version
              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.

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

       source:Extended-Description
              The   source  package  extended  description,  extracted  from  the  source  stanza
              Description field, if it exists (since dpkg 1.19.0).

       Installed-Size
              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.

              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.

       Extra-Size
              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.

       S:fieldname
              The value of the source  stanza  field  fieldname  (which  must  be  given  in  the
              canonical  capitalisation;  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 files.

       F:fieldname
              The  value  of  the  output  field  fieldname (which must be given in the canonical
              capitalisation). Setting these variables has no effect other than on  places  where
              they are expanded explicitly.

       Format 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 too.

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

       shlibs:dependencyfield
              Variable settings with names of this form are generated by dpkg-shlibdeps.

       dpkg:Upstream-Version
              The upstream version of dpkg (since dpkg 1.13.19).

       dpkg:Version
              The full version of dpkg (since dpkg 1.13.19).

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

FILES

       debian/substvars
              List of substitution variables and values.

SEE ALSO

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