Question

I have a standard passwd file & a usermap file – which maps unix name (eg jbloggs) with AD account name (eg bloggsjoe) in the format:
jbloggs bloggsjoe
jsmith smithjohn
… etc.
How can I edit the passwd file to swap the original unix name with the AD account name so each line of the passwd file has the AD account name instead.
Appreciate any help for a perl learner.

Answer 1

here’s a awk one liner to do that

$ cat map.txt
jbloggs bloggsjoe
jsmith smithjohn

$ cat passwd
root:x:0:0:root:/root:/bin/bash
jbloggs:x:493:484:Blogger:/var/run/lib:/sbin/nologin
jsmith:x:27:481:MySQL Server user:/var/lib/mysql:/bin/bash

$ awk -F":" 'FNR==NR{gsub(" +",":");m[$1]=$2;next}($1 in m){$1=m[$1]}1' OFS=":"  map.txt passwd
root:x:0:0:root:/root:/bin/bash
bloggsjoe:x:493:484:Blogger:/var/run/lib:/sbin/nologin
smithjohn:x:27:481:MySQL Server user:/var/lib/mysql:/bin/bash