diff options
Diffstat (limited to 'doc/tar.texi')
| -rw-r--r-- | doc/tar.texi | 44 |
1 files changed, 39 insertions, 5 deletions
diff --git a/doc/tar.texi b/doc/tar.texi index 993db4cf..72d6aeeb 100644 --- a/doc/tar.texi +++ b/doc/tar.texi @@ -2407,7 +2407,8 @@ superuser privileges and can be a pain to manage. @itemx -a During a @option{--create} operation, enables automatic compressed -format recognition based on the archive suffix. @xref{gzip}. +format recognition based on the archive suffix. The effect of this +option is cancelled by @option{--no-auto-compress}. @xref{gzip}. @opsummary{backup} @item --backup=@var{backup-type} @@ -2785,10 +2786,16 @@ incremental format. @xref{Incremental Dumps}. @opsummary{lzma} @item --lzma +@itemx -J This option tells @command{tar} to read or write archives through @command{lzma}. @xref{gzip}. +@item --lzop + +This option tells @command{tar} to read or write archives through +@command{lzop}. @xref{gzip}. + @opsummary{mode} @item --mode=@var{permissions} @@ -2843,6 +2850,12 @@ changed). @xref{after}. An exclude pattern can match any subsequence of the name's components. @xref{controlling pattern-matching}. +@opsummary{no-auto-compress} +@item --no-auto-compress + +Disables automatic compressed format recognition based on the archive +suffix. @xref{--auto-compress}. @xref{gzip}. + @opsummary{no-check-device} @item --no-check-device Do not check device numbers when creating a list of modified files @@ -3358,6 +3371,8 @@ them with the equivalent long option. @item -G @tab @ref{--incremental}. +@item -J @tab @ref{--lzma}. + @item -K @tab @ref{--starting-file}. @item -L @tab @ref{--tape-length}. @@ -3411,7 +3426,7 @@ them with the equivalent long option. @item -o @tab When creating, @ref{--no-same-owner}, when extracting --- @ref{--portability}. -The later usage is deprecated. It is retained for compatibility with +The latter usage is deprecated. It is retained for compatibility with the earlier versions of @GNUTAR{}. In future releases @option{-o} will be equivalent to @option{--no-same-owner} only. @@ -8257,8 +8272,13 @@ switch to @samp{posix}. @cindex Compressed archives @cindex Storing archives in compressed format +@cindex gzip +@cindex bzip2 +@cindex lzma +@cindex lzop +@cindex compress @GNUTAR{} is able to create and read compressed archives. It supports -@command{gzip}, @command{bzip2} and @command{lzma} compression +@command{gzip}, @command{bzip2}, @command{lzma} and @command{lzop} compression programs. For backward compatibility, it also supports @command{compress} command, although we strongly recommend against using it, because it is by far less effective than other compression @@ -8269,7 +8289,8 @@ Creating a compressed archive is simple: you just specify a commands. The compression option is @option{-z} (@option{--gzip}) to create a @command{gzip} compressed archive, @option{-j} (@option{--bzip2}) to create a @command{bzip2} compressed archive, -@option{--lzma} to create an @asis{LZMA} compressed archive and +@option{-J} (@option{--lzma}) to create an @asis{LZMA} compressed +archive, @option{--lzop} to create an @asis{LSOP} archive, and @option{-Z} (@option{--compress}) to use @command{compress} program. For example: @@ -8309,6 +8330,12 @@ $ @kbd{tar tf archive.tar.gz} $ @kbd{tar xf archive.tar.gz} @end smallexample +The format recognition algorithm is based on @dfn{signatures}, a +special byte sequences in the beginning of file, that are specific for +certain compression formats. If this approach fails, @command{tar} +falls back to using archive name suffix to determine its format +(@xref{auto-compress}, for a list of recognized suffixes). + 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{} @@ -8344,7 +8371,7 @@ The following table summarizes compression options used by @GNUTAR{}. @item --auto-compress @itemx -a Select a compression program to use by the archive file name -suffix. The following suffixes are recognized: +suffix. The following suffixes are recognized: @multitable @columnfractions 0.3 0.6 @headitem Suffix @tab Compression program @@ -8359,6 +8386,7 @@ suffix. The following suffixes are recognized: @item @samp{.tbz} @tab @command{bzip2} @item @samp{.lzma} @tab @command{lzma} @item @samp{.tlz} @tab @command{lzma} +@item @samp{.lzo} @tab @command{lzop} @end multitable @opindex gzip @@ -8409,8 +8437,14 @@ Filter the archive through @code{bzip2}. Otherwise like @option{--gzip}. @opindex lzma @item --lzma +@itemx -J Filter the archive through @command{lzma}. Otherwise like @option{--gzip}. +@opindex lzop +@item --lzop +Filter the archive through @command{lzop}. Otherwise like +@option{--gzip}. + @opindex compress @opindex uncompress @item -Z |