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9.4 Invoking the msgfilter Program

     msgfilter [option] filter [filter-option]

The msgfilter program applies a filter to all translations of a translation catalog.

During each filter invocation, the environment variable MSGFILTER_MSGID is bound to the message's msgid, and the environment variable MSGFILTER_LOCATION is bound to the location in the PO file of the message. If the message has a context, the environment variable MSGFILTER_MSGCTXT is bound to the message's msgctxt, otherwise it is unbound.

9.4.1 Input file location

-i inputfile
--input=inputfile
Input PO file.
-D directory
--directory=directory
Add directory to the list of directories. Source files are searched relative to this list of directories. The resulting .po file will be written relative to the current directory, though.

If no inputfile is given or if it is ‘-’, standard input is read.

9.4.2 Output file location

-o file
--output-file=file
Write output to specified file.

The results are written to standard output if no output file is specified or if it is ‘-’.

9.4.3 The filter

The filter can be any program that reads a translation from standard input and writes a modified translation to standard output. A frequently used filter is ‘sed’. A few particular built-in filters are also recognized.

Note: If the filter is not a built-in filter, you have to care about encodings: It is your responsibility to ensure that the filter can cope with input encoded in the translation catalog's encoding. If the filter wants input in a particular encoding, you can in a first step convert the translation catalog to that encoding using the ‘msgconv’ program, before invoking ‘msgfilter’. If the filter wants input in the locale's encoding, but you want to avoid the locale's encoding, then you can first convert the translation catalog to UTF-8 using the ‘msgconv’ program and then make ‘msgfilter’ work in an UTF-8 locale, by using the LC_ALL environment variable.

Note: Most translations in a translation catalog don't end with a newline character. For this reason, it is important that the filter recognizes its last input line even if it ends without a newline, and that it doesn't add an undesired trailing newline at the end. The ‘sed’ program on some platforms is known to ignore the last line of input if it is not terminated with a newline. You can use GNU sed instead; it does not have this limitation.

9.4.4 Useful filter-options when the filter is ‘sed

-e script
--expression=script
Add script to the commands to be executed.
-f scriptfile
--file=scriptfile
Add the contents of scriptfile to the commands to be executed.
-n
--quiet
--silent
Suppress automatic printing of pattern space.

9.4.5 Built-in filters

The filter ‘recode-sr-latin’ is recognized as a built-in filter. The command ‘recode-sr-latin’ converts Serbian text, written in the Cyrillic script, to the Latin script. The command ‘msgfilter recode-sr-latin’ applies this conversion to the translations of a PO file. Thus, it can be used to convert an sr.po file to an sr@latin.po file.

The use of built-in filters is not sensitive to the current locale's encoding. Moreover, when used with a built-in filter, ‘msgfilter’ can automatically convert the message catalog to the UTF-8 encoding when needed.

9.4.6 Input file syntax

-P
--properties-input
Assume the input file is a Java ResourceBundle in Java .properties syntax, not in PO file syntax.
--stringtable-input
Assume the input file is a NeXTstep/GNUstep localized resource file in .strings syntax, not in PO file syntax.

9.4.7 Output details

--color
--color=when
Specify whether or when to use colors and other text attributes. See The –color option for details.
--style=style_file
Specify the CSS style rule file to use for --color. See The –style option for details.
--force-po
Always write an output file even if it contains no message.
--indent
Write the .po file using indented style.
--keep-header
Keep the header entry, i.e. the message with ‘msgid ""’, unmodified, instead of filtering it. By default, the header entry is subject to filtering like any other message.
--no-location
Do not write ‘#: filename:line’ lines.
--add-location
Generate ‘#: filename:line’ lines (default).
--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.
-p
--properties-output
Write out a Java ResourceBundle in Java .properties syntax. Note that this file format doesn't support plural forms and silently drops obsolete messages.
--stringtable-output
Write out a NeXTstep/GNUstep localized resource file in .strings syntax. Note that this file format doesn't support plural forms.
-w number
--width=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 number.
--no-wrap
Do not break long message lines. Message lines whose width exceeds the output page width will not be split into several lines. Only file reference lines which are wider than the output page width will be split.
-s
--sort-output
Generate sorted output. Note that using this option makes it much harder for the translator to understand each message's context.
-F
--sort-by-file
Sort output by file location.

9.4.8 Informative output

-h
--help
Display this help and exit.
-V
--version
Output version information and exit.

9.4.9 Examples

To convert German translations to Swiss orthography (in an UTF-8 locale):

     msgconv -t UTF-8 de.po | msgfilter sed -e 's/ß/ss/g'

To convert Serbian translations in Cyrillic script to Latin script:

     msgfilter recode-sr-latin < sr.po