Re: [Help-tar] Trouble with tar -xzf when using --files-from=-

[Reuti]

Hi,


> Am 21.10.2015 um 03:20 schrieb Tony Olekshy <address@hidden>:
> 
> Hello.
> 
> I'm having trouble understanding why I can't pipe the output of a
> tar -tzf a.tgz ... through to a tar -xzf a.tgz --files=from=- ...
> without producing what appear to be spurious messages. In practice
> I want to place a filter in that pipeline to select just what to
> extract, but the following script simplifies that out to just show
> the problem I'm encountering.

Accessing "." in the archive will move its pointer already to the end:

$ echo . | tar tf archive.tgz --files-from=-
./
./foo/
./foo/bar

BTW: there is the option -C to easy to write to any directory with `tar`.

-- Reuti


> Here are my test script and my questions thereto. Any insight you
> can provide me with would be appreciated.
> 
> #!/bin/bash
> #-----------------------------------------------------------------------
> #
> #   Subject: Trouble with tar -xzf when using --files-from=-
> #
> #   From Tony Olekshy, Avra Software Lab Inc., 2015-10-20.
> #
> #   The following has been reproduced with the GNU tar 1.26 that came
> #   with Fedora release 18, with GNU tar 1.27.1 and 1.28 which I just
> #   compiled on Fedora release 18, and with the GNU tar 1.23 that came
> #   with Red Hat Enterprise Linux Server release 6.6.
> #
> #   Step 5 below produces these messages:
> #
> #       tar: ./foo: Not found in archive
> #       tar: ./foo/bar: Not found in archive
> #       tar: Exiting with failure status due to previous errors
> #
> #   But step 6 shows that ./foo & ./foo/bar were in fact correctly
> #   extracted into $TEST/into, so they were found in the archive!
> #
> #   My questions are: Why does step 5 produce those messages?
> #   What am I misunderstanding, or is there some bug in tar?
> #
> set -v #----------------------------------------------------------------
> 
> : Step 1: Create the testing environment...
> :
> export TAR=/bin/tar TEST=~/test
> 
> echo; $TAR --version | grep 'GNU tar'
> 
> mkdir -p $TEST/from/foo $TEST/into
> rm -rf $TEST/archive.tgz $TEST/into/*
> date > $TEST/from/foo/bar
> 
> : Step 2: Show the contents of $TEST...
> :
> echo; cd $TEST; find . | sort | xargs ls -ld
> 
> : Step 3: Create $TEST/archive.tgz...
> :
> cd $TEST/from; find .   \
>                        \
>    | $TAR -vczf $TEST/archive.tgz --files-from=- --no-recursion
> 
> : Step 4: Show the contents of archive.tgz...
> :
> cd $TEST; $TAR -tzf $TEST/archive.tgz
> 
> : Step 5: Extract files from archive.tgz using --files-from...
> :
> cd $TEST; $TAR -tzf $TEST/archive.tgz | ( cd $TEST/into;
> 
>    $TAR -vxzf $TEST/archive.tgz --files-from=- --no-recursion )
> 
> : Step 6: Show the contents of $TEST...
> :
> echo; cd $TEST; find . | sort | xargs ls -ld
> 
> exit #------------------------------------------------------------------
> 
> Here is the output from running that script...
> 
> : Step 1: Create the testing environment...
> :
> export TAR=/bin/tar TEST=~/test
> 
> echo; $TAR --version | grep 'GNU tar'
> 
> tar (GNU tar) 1.26
> 
> mkdir -p $TEST/from/foo $TEST/into
> rm -rf $TEST/archive.tgz $TEST/into/*
> date > $TEST/from/foo/bar
> 
> : Step 2: Show the contents of $TEST...
> :
> echo; cd $TEST; find . | sort | xargs ls -ld
> 
> drwxr-x--- 4 olekshy olekshy 4096 Oct 20 18:52 ./
> drwxr-x--- 3 olekshy olekshy 4096 Oct 20 18:37 ./from/
> drwxr-x--- 2 olekshy olekshy 4096 Oct 20 18:37 ./from/foo/
> -rw-r----- 1 olekshy olekshy   29 Oct 20 18:52 ./from/foo/bar
> drwxr-x--- 2 olekshy olekshy 4096 Oct 20 18:52 ./into/
> 
> : Step 3: Create $TEST/archive.tgz...
> :
> cd $TEST/from; find .   \
>                        \
>    | $TAR -vczf $TEST/archive.tgz --files-from=- --no-recursion
> ./
> ./foo/
> ./foo/bar
> 
> : Step 4: Show the contents of archive.tgz...
> :
> cd $TEST; $TAR -tzf $TEST/archive.tgz
> ./
> ./foo/
> ./foo/bar
> 
> : Step 5: Extract files from archive.tgz using --files-from...
> :
> cd $TEST; $TAR -tzf $TEST/archive.tgz | ( cd $TEST/into;
> 
>    $TAR -vxzf $TEST/archive.tgz --files-from=- --no-recursion )
> ./
> ./foo/
> ./foo/bar
> /bin/tar: ./foo: Not found in archive
> /bin/tar: ./foo/bar: Not found in archive
> /bin/tar: Exiting with failure status due to previous errors
> 
> : Step 6: Show the contents of $TEST...
> :
> echo; cd $TEST; find . | sort | xargs ls -ld
> 
> drwxr-x--- 4 olekshy olekshy 4096 Oct 20 18:52 ./
> -rw-r----- 1 olekshy olekshy  195 Oct 20 18:52 ./archive.tgz
> drwxr-x--- 3 olekshy olekshy 4096 Oct 20 18:37 ./from/
> drwxr-x--- 2 olekshy olekshy 4096 Oct 20 18:37 ./from/foo/
> -rw-r----- 1 olekshy olekshy   29 Oct 20 18:52 ./from/foo/bar
> drwxr-x--- 3 olekshy olekshy 4096 Oct 20 18:37 ./into/
> drwxr-x--- 2 olekshy olekshy 4096 Oct 20 18:37 ./into/foo/
> -rw-r----- 1 olekshy olekshy   29 Oct 20 18:52 ./into/foo/bar
> 
> exit #------------------------------------------------------------------
> 
> Sincerely Yours,
> Tony Olekshy
> Avra Software Lab Inc.
>