I archived a directory. It took two hours, then exited with a non-zero exit status (that means an error). Hmm — I was just testing something; I only cared if certain specific subdirectories were present in the archive. So I needed a way to look deep inside, quickly, and find those particular directories.
GNU tar will let you “test” an archive with -t, but I only wanted a list of the directories archived. Then I wanted that sorted. So…
$ nice tar -tjvf data.tar.bz2 | tr -s ' ' | cut -d' ' -f 6- | cut -d / -f -2 > tardirs.txt
$ uniq tardirs.txt > tardirs_uniq.txt
$ sort tardirs_uniq.txt > tardirs_uniq_sorted.txt
The -tjvf arguments to tar let you look inside, the “tr” command collapses adjacent spaces so that the first “cut” command will output only the sixth (file) field, and the second “cut” command will reduce a directory like “folder/folder/folder/fun.txt” to “folder/folder.” Then “uniq” will remove non-unique names.
If you’d like to start an Ubuntu service using the System V-compatible runlevels, use “update-rc.d.” For example:
# update-rc.d ssh defaults
update-rc.d: warning: ssh stop runlevel arguments (0 1 6) do not match LSB Default-Stop values (none)
Adding system startup for /etc/init.d/ssh ...
/etc/rc0.d/K20ssh -> ../init.d/ssh
/etc/rc1.d/K20ssh -> ../init.d/ssh
/etc/rc6.d/K20ssh -> ../init.d/ssh
/etc/rc2.d/S20ssh -> ../init.d/ssh
/etc/rc3.d/S20ssh -> ../init.d/ssh
/etc/rc4.d/S20ssh -> ../init.d/ssh
/etc/rc5.d/S20ssh -> ../init.d/ssh