Problem creating a tar ball in different directories

Shell Programming and Scripting
1

Hi all. I'm hitting a problem creating a tar archive in one directory from files located in a different directory. It fails when I replace the absolute paths with variables in the script but works if I just run tar on the cmdln. E.g.

#!/bin/ksh

BASE=$PWD
STAGE=$BASE/stage
LOG=$BASE/log
FILENAME=test.tar.gz

$(tar -zcvf $STAGE/${FILENAME} ${LOG}/*)

This gives the following error

tar: Removing leading `/' from member names

I saw some posts about this saying to use -C but that didn't help. Also, tried to change dir in to the log dir and run e.g.

$(cd $LOG && tar -zcvf $STAGE/${FILENAME} *)

but that gives an error, although it appear to actually create the gz file correctly.

 "./a.ksh[11]: a.b: not found [No such file or directory]"

where a.b is the file in the log sub dir that's being tarred.

2

I don't understand why you have your tar command embedded in a process substitution:

$(tar -zcvf $STAGE/${FILENAME} ${LOG}/*)

This would cause the output of tar (and you have it in verbose mode) being collected into a shell-variable:

tar_log=$(tar -zcvf $STAGE/${FILENAME} ${LOG}/*)

As you are not doing this I can only imagine the output of tar is being interpreted by your shell process.

As for the leading "/" error, tar is attempting to prevent absolute file paths to be entered into the archive so you don't overwrite anything when extracting the archive. I don't know the -C switch but imagine it should be used thus:

tar -zcv -C ${LOG} -f ${STAGE}/${FILENAME} .

Andrew

1 Like
3

Good points Andrew. Thanks.

Yeah the 'tar: Removing leading `/' from member names' warning is there for our own benefit so I guess it's simpler to just do everything in 3 steps and get around any issues ...

cd ${LOG} && tar -zcf ${FILENAME} * && cp ${FILENAME} ${STAGE}
4

How about pax
The compression is not POSIX, but it should work almost everywhere.
Notice you cannot append to compressed archive with pax, if you require such feature.

pax -wzf ${STAGE}/mybackup.tar.gz  ${LOG}

Will create compressed archive from ${LOG} directory (everything in it) into ${STAGE}/mybackup.tar.gz

It also supports to substitute paths inside archive in one go, and a lot more, in one line.
Check it out online or on these forums!

Hope that helps
Regards
Peasant.

5

No, use the absolute path for the target tarball (as in my example).

Andrew