Shell Programming and Scripting

Well I use it almost that way when I transfer filesystems, directories.. to a remote destination e.g.

Code:

cd sourcedir; 
tar -cf -  * | remsh dest_node "(cd destdir; tar -xvf - )"

But locally, for same usage I privilege cpio ....

@vbe: I stumbled over exactly the same stone, as I did transfers a lot in the way you mention. BUT - alister said "tar doesn't read FILENAMES from stdin"; this is different to "tar reading archivable contents from stdin", and I believe he's right.

Hi all,
I used this

Code:

cd /var/spool/cron/crontabs
sudo tar cvf /users/mahesh/all_cron.tar `ls -ltr * |grep -v .au |awk '{print $9}'`

This is a Sun Solaris 10 machine.

Ah yes, I misunderstood... Thanks for noticing...

That solution is incorrect. Your grep invocation can exclude files which should not be excluded. While the regular expression .au will correctly exclude files ending with ".au", it will also exclude a file which contains any character followed by "au" at any point in the file name, such as myaudio.sh.

The correct approach requires backslash escaping the dot so that it is taken literally, and anchoring the regular expression to the end of the line:

Code:

grep -v '\.au$'

Not of much importance, but there's no need to sort ls' output; -t and -r can be omitted. Further, since only the file name is of interest, no need for the long listing format, so -l can be dropped as well. Dropping the long listing format obviates the need for AWK, reducing your approach to:

Code:

ls | grep -v '\.au$'

However, I wouldn't use this command substitution approach. For years now, Solaris (and nearly every UNIX-like system, except perhaps for a few linux distributions) has shippied with pax. I'd just use that.

Code:

cd /var/spool/cron/crontabs && pax -ws '/.*\.au$//' . > /users/mahesh/all_cron.tar

As added bonuses, now neither a large number of files nor files with whitespace will break the archiving attempt.

Regards,
Alister