[SOLVED] How to extract particular string from a file (linux)

Issue

I have the following file

vol-12345678    gp2
vol-89dfg58g
VOLUMES 2016-03-17T22:03:08.374Z  False   100     16      snap-7073d522   in-use  vol-4568gds4    gp2
ATTACHMENTS     2016-03-17T22:03:08.000Z        True    /dev/sda1       i-181ed33c      attached        vol-7ea1c83f

etc.

etc.

I want to extract all instances of 'vol-********' and output it to a file (without the other contents) resulting in a file of:

vol-12345678

vol-34556767

vol-34534sdf

...

This is a relatively small file so I could do it manually, but I have another file with 200+ cases. Any idea how to use this using GREP or SED or AWK? Thanks!

Solution

UPDATE Command:

sed -n 's/.*\b\(vol-[[:alnum:]]*\).*/\1/'p test2

Output:

vol-12345678
vol-89dfg58g
vol-4568gds4
vol-7ea1c83f

Flags: n : Suppress automatic printing of pattern space. p : Print out the pattern space

Pattern:

• Look for 'vol-[alphanumeric]s'
• Substitute it and print the first match with \1

More details Sed

Answered By - Avikd