Grepping a word using sed (BASH)

cat /etc/passwd

kernoops:x:109:65534:Kernel Oops Tracking Daemon,,,:/:/bin/false
pulse:x:110:119:PulseAudio daemon,,,:/var/run/pulse:/bin/false
rtkit:x:111:122:RealtimeKit,,,:/proc:/bin/false
saned:x:112:123::/home/saned:/bin/false
speech-dispatcher:x:113:29:Speech Dispatcher,,,:/var/run/speech-dispatcher:/bin/sh
hplip:x:114:7:HPLIP system user,,,:/var/run/hplip:/bin/false
ntp:x:115:124::/home/ntp:/bin/false
puppet:x:116:125:Puppet configuration management daemon,,,:/var/lib/puppet:/bin/false
clamav:x:117:126::/var/lib/clamav:/bin/false
sshd:x:118:65534::/var/run/sshd:/usr/sbin/nologin
git:x:1000:1001:sam,111,211,233,nothing:/home/git:/bin/bash
jenkins:x:119:128::/var/lib/jenkins:/bin/bash
postfix:x:120:130::/var/spool/postfix:/bin/false


 

cat /etc/passwd | sed -n 's/.*\([a-z]\{13\}\)[[:space:]]\([a-z]*\)[[:space:]]\([a-z]*\).*/\1 \3/p'

configuration daemon


\([a-z]\{13\}\)      Configuration --> \1  first matched group pattern

 ([a-z]*\)               daemon --> \2 second matched group pattern