@example
msgmerge [@var{option}] @var{def}.po @var{ref}.pot
@end example

The @code{msgmerge} program merges two Uniforum style .po files together.
The @var{def}.po file is an existing PO file with translations which will
be taken over to the newly created file as long as they still match;
comments will be preserved, but extracted comments and file positions will
be discarded.  The @var{ref}.pot file is the last created PO file with
up-to-date source references but old translations, or a PO Template file
(generally created by @code{xgettext}); any translations or comments
in the file will be discarded, however dot comments and file positions
will be preserved.  Where an exact match cannot be found, fuzzy matching
is used to produce better results.

@subsection Input file location

@table @samp
@item @var{def}.po
Translations referring to old sources.

@item @var{ref}.pot
References to the new sources.

@item -D @var{directory}
@itemx --directory=@var{directory}
Add @var{directory} to the list of directories.  Source files are
searched relative to this list of directories.  The resulting @file{.po}
file will be written relative to the current directory, though.

@item -C @var{file}
@itemx --compendium=@var{file}
Specify an additional library of message translations.  @xref{Compendium}.
This option may be specified more than once.

@end table

@subsection Operation mode

@table @samp
@item -U
@itemx --update
Update @var{def}.po.  Do nothing if @var{def}.po is already up to date.

@end table

@subsection Output file location

@table @samp
@item -o @var{file}
@itemx --output-file=@var{file}
Write output to specified file.

@end table

The results are written to standard output if no output file is specified
or if it is @samp{-}.

@subsection Output file location in update mode

The result is written back to @var{def}.po.

@table @samp
@item --backup=@var{control}
Make a backup of @var{def}.po

@item --suffix=@var{suffix}
Override the usual backup suffix.

@end table

The version control method may be selected via the @code{--backup} option
or through the @code{VERSION_CONTROL} environment variable.  Here are the
values:

@table @samp
@item none
@itemx off
Never make backups (even if @code{--backup} is given).

@item numbered
@itemx t
Make numbered backups.

@item existing
@itemx nil
Make numbered backups if numbered backups for this file already exist,
otherwise make simple backups.

@item simple
@itemx never
Always make simple backups.

@end table

The backup suffix is @samp{~}, unless set with @code{--suffix} or the
@code{SIMPLE_BACKUP_SUFFIX} environment variable.

@subsection Operation modifiers

@table @samp
@item -m
@itemx --multi-domain
Apply @var{ref}.pot to each of the domains in @var{def}.po.

@end table

@subsection Output details

@c --no-escape and --escape omitted on purpose.  They are not useful.

@table @samp
@item --force-po
Always write an output file even if it contains no message.

@item -i
@itemx --indent
Write the .po file using indented style.

@item --no-location
Do not write @samp{#: @var{filename}:@var{line}} lines.

@item --add-location
Generate @samp{#: @var{filename}:@var{line}} lines (default).

@item --strict
Write out a strict Uniforum conforming PO file.  Note that this
Uniforum format should be avoided because it doesn't support the
GNU extensions.

@item -w @var{number}
@itemx --width=@var{number}
Set the output page width.  Long strings in the output files will be
split across multiple lines in order to ensure that each line's width
(= number of screen columns) is less or equal to the given @var{number}.

@item -s
@itemx --sort-output
Generate sorted output.  Note that using this option makes it much harder
for the translator to understand each message's context.

@item -F
@itemx --sort-by-file
Sort output by file location.

@end table

@subsection Informative output

@table @samp
@item -h
@itemx --help
Display this help and exit.

@item -V
@itemx --version
Output version information and exit.

@item -v
@itemx --verbose
Increase verbosity level.

@item -q
@itemx --quiet
@itemx --silent
Suppress progress indicators.

@end table