Text Manipulation using sed or AWK

Question

I get the following result in my script when I run it against my services. The result differs depending on the service but the text pattern showing below is similar. The result of my script is assigned to var1. I need to extract data from this variable

$var1=HOST1*prod*gem.dot*serviceList : svc1 HOST1*prod*kem.dot*serviceList : svc3, svc4    HOST1*prod*fen.dot*serviceList : svc5, svc6

I need to strip the name of the service list from $var1. So the end result should be printed on separate line as follow:

svc1 
svc2
svc3
svc4
svc5
svc6

Can you please help with this?

Regards

Answer 1

Using sed and grep:

sed 's/[^ ]* :\|,\|//g' <<< "$var1" | grep -o '[^ ]*'

sed deletes every non-whitespace before a colon and commas. Grep just outputs the resulting services one per line.

Answer 2

Using gnu grep and gnu sed:

grep -oP ': *\K\w+(, \w+)?' <<< "$var1" | sed 's/, /\n/'
svc1
svc3
svc4
svc5
svc6

Answer 3

grep is the perfect tool for the job.

From man grep:

-o, --only-matching
Print only the matched (non-empty) parts of a matching line, with each such part on a separate output line.

Sounds perfect!

As far as I'm aware this will work on any grep:

echo "$var1" | grep -o 'svc[0-9]\+'

Matches "svc" followed by one or more digits. You can also enable the "highly experimental" Perl regexp mode with -P, which means you can use the \d digit character class and don't have to escape the + any more:

grep -Po 'svc\d+' <<<"$var1"

In bash you can use <<< (a Here String) which supplies "$var1" to grep on the standard input.

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By the way, if your data was originally on separate lines, like:

HOST1*prod*gem.dot*serviceList : svc1 
HOST1*prod*kem.dot*serviceList : svc3, svc4    
HOST1*prod*fen.dot*serviceList : svc5, svc6

This would be a good job for awk:

awk -F': ' '{split($2,a,", "); for (i in a) print a[i]}'