Question

I have the below output

Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/sda3             60300484  18883824  38304156  34% /
/dev/sda1              1046516      8604   1037912   1% /boot/efi
tmpfs                  4120800         0   4120800   0% /dev/shm
psnfs1:/SDepot     629145600 400663744 228481856  64% /depot
psnfs1:/vol/ghome/ghome/support/kumar
                     1287651328 1065510400 222140928  83% /home/kumar
psnfs2:/vol/us_nhome2/us_nishome2/shaw
                     1073741888 799816192 273925696  75% /home/shaw
psnfs2:/vol/us_nhome2/us_nishome2/asimon
                     1073741888 799816192 273925696  75% /home/asimon

Where I am using (?xms)(^[/\w:]+.*?)(?=^[/\w:]+|\Z) to get each row, later i use \s to extract each column values from the prev regex output, but the problem is I also get the headings (Filesystem 1K-blocks Used Available Use% Mounted on). How can i omit them? Also explain the regex please 🙂 Thanks

Answer 1

If you’re building this into a shell pipeline, it’d probably be easier to use tail(1) than building an even more complicated regex:

$ df -k
Filesystem           1K-blocks      Used Available Use% Mounted on
/dev/sda3             11811504   7979960   3231544  72% /
none                   3054508       300   3054208   1% /dev
...

vs

$ df -k | tail -n+2
/dev/sda3             11811504   7979960   3231544  72% /
none                   3054508       300   3054208   1% /dev
none                   3061428       596   3060832   1% /dev/shm
...

From the tail(1) manpage:

   -n, --lines=K
          output the last K lines, instead of the last 10; or
          use -n +K to output lines starting with the Kth

And if it were me, I’d probably use awk(1) to get to specific columns:

$ df -k |tail -n+2 | awk '{print $5, $6;}'
72% /
1% /dev
1% /dev/shm
1% /var/run
0% /var/lock
72% /var/lib/ureadahead/debugfs
59% /boot
34% /home