awk/sed help

oliveoyl · 03-08-2019, 02:21 PM

Hello,

I have a file with 4 fields below. I need to run 'getent passwd uid' on each line and get the full name (gecos) then append it to the file correctly:

uid1 group1 25464.6 44044
uid2 group2 28680.9 60231
uid3 group3 28768.3 50

I can run a loop on uids and getent passwd then awk it to get the gecos but how do I append it back to the original file?

Looking to get this:

"First Last" uid1 group1 25464.6 44044
Jon Doe uid2 group2 28680.9 60231
Jane Doe uid3 group3 28768.3 50

rtmistler · 03-08-2019, 02:33 PM

I know in sed, you use ^ to mean the beginning of a line, so you can do like:

Code:

sed 's/^/new text/' <filename>

But that would work for every line, not just the ones you want. So in this case, I'd guess that instead would be:

Code:

sed 's/$uid1/added text $uid1/'

And have $uid1 be a variable which contains the found UID that you got from each line.

teckk · 03-08-2019, 02:34 PM

read
man awk
man sed

Simple example:

Code:

list=("uid1 group1 25464.6 44044"
"uid2 group2 28680.9 60231"
"uid3 group3 28768.3 50")

echo "${list[0]}" | sed 's/^/First Last /'
echo "${list[1]}" | awk '{print "Jon Doe " $0}'

Turbocapitalist · 03-08-2019, 03:18 PM

Which version of AWK do you have? Perhaps you could do something like this with it:

Code:

awk '{cmd="id -u -n " $1; cmd|getline a; print a,$0;}'

That is with the utility id, but hopefully it shows the idea.

As suggested, see "man awk" for the details on the version of AWK you have.

allend · 03-08-2019, 07:53 PM

I would just use a bash script.

Code:

#!/bin/bash

while read u g k l; do
 en=$(getent passwd "$u")
 if [[ "$en" =~ :([[:upper:]][^,]*) ]]; then
  name=${BASH_REMATCH[1]}
  echo "\"$name\" $u $g $k $l"
 else
  echo "No match for $u"
 fi
done < input_file

The pattern match assumes that the full name starts with an upper case character.