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

       deb-substvars - Debian source substitution variables


       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  (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

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

       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.

       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).

              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.

              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 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.

              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

       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).

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

              List of substitution variables and values.

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

1.19.7                            2022-05-25                  deb-substvars(5)
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