diff options
Diffstat (limited to 'doc/tar.texi')
| -rw-r--r-- | doc/tar.texi | 35 |
1 files changed, 35 insertions, 0 deletions
diff --git a/doc/tar.texi b/doc/tar.texi index 6d9d9cc5..2c259ff9 100644 --- a/doc/tar.texi +++ b/doc/tar.texi @@ -4166,6 +4166,23 @@ Disable all warning messages. @cindex @samp{Ignoring unknown extended header keyword `%s'}, warning message @item unknown-keyword @samp{Ignoring unknown extended header keyword `%s'} +@kwindex decompress-program +@item decompress-program +Controls verbose messages describing execution failures when trying +alternative decompressor programs (@pxref{alternative decompression +programs}). This warning is disabled by default (unless +@option{--verbose} is used). A common example of what you can get +when using this warning is: + +@smallexample +$ @kbd{tar --warning=decompress-program -x -f archive.Z} +tar (child): cannot run compress: No such file or directory +tar (child): trying gzip +@end smallexample + +This means that @command{tar} first tried to decompress +@file{archive.Z} using @command{compress}, and, when that +failed, switched to @command{gzip}. @end table @subheading Keywords controlling incremental extraction: @@ -8755,6 +8772,24 @@ certain compression formats. If this approach fails, @command{tar} falls back to using archive name suffix to determine its format (@pxref{auto-compress}, for a list of recognized suffixes). +@anchor{alternative decompression programs} +@cindex alternative decompression programs +Some compression programs are able to handle different compression +formats. @GNUTAR{} uses this, if the principal decompressor for the +given format is not available. For example, if @command{compress} is +not installed, @command{tar} will try to use @command{gzip}. As of +version @value{VERSION} the following alternatives are +tried@footnote{To verbosely trace the decompressor selection, use the +@option{--warning=decompress-program} option +(@pxref{warnings,decompress-program}).}: + +@multitable @columnfractions 0.3 0.3 0.3 +@headitem Format @tab Main decompressor @tab Alternatives +@item compress @tab compress @tab gzip +@item lzma @tab lzma @tab xz +@item bzip2 @tab bzip2 @tab lbzip2 +@end multitable + The only case when you have to specify a decompression option while reading the archive is when reading from a pipe or from a tape drive that does not support random access. However, in this case @GNUTAR{} |