Filtering Linux command output

Question

I need to get a row based on column value just like querying a database. I have a command output like this,

Name ID Mem VCPUs State
Time(s)

Domain-0 0 15485 16 r----- 1779042.1

prime95-01 512 1
-b---- 61.9

Here I need to list only those rows where state is "r". Something like this,

Domain-0 0 15485 16
r----- 1779042.1

I have tried using "grep" and "awk" but still I am not able to succeed.

Please help me on this issue.

Regards, Raaj

Answer 1

There is a variaty of tools available for filtering.

If you only want lines with "r-----" grep is more than enough:

command | grep "r-----"

Or

cat filename | grep "r-----"

Quotes are optional but might prevent grep tripping over the -'s

Answer 2

grep can handle this for you:

yourcommand | grep -- 'r-----'

It's often useful to save the (full) output to a file to analyse later. For this I use tee.

yourcommand | tee somefile | grep 'r-----'

If you want to find the line containing "-b----" a little later on without re-running yourcommand, you can just use:

grep -- '-b----' somefile

No need for cat here!

I recommend putting -- after your call to grep since your patterns contain minus-signs and if the minus-sign is at the beginning of the pattern, this would look like an option argument to grep rather than a part of the pattern.