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I'm new to scripting, so far I've created this:

#!/bin/sh
(
echo List of users in PRD 

echo $(date)

cat /etc/passwd | awk -F: '{print $1,$3,$5}' | sort | \
while read username uid gecos
do
echo "${username}:${uid}:${gecos}"
done
) > `hostname`_userlogins.txt
mailx -s file [email protected] < `hostname`_userlogins.txt

This gives a list of all users. I have another file (called ignore.txt) which has list of users to be excluded before sending the email out.

How do I link the list with ignore.txt to filter?

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You can use grep to filter out usernames:

grep -wvf ignore.txt /etc/passwd | awk ...

grep is used to search for patterns usually, but with -v can be used to negate the search, and thus for filtering. The matches can be a bit broad (for example, joe will filter out joe and joey), so use -w to restrict its effect to whole-word matches.

Other suggestions:

  • awk can be told to print with colons, saving you the trouble of the loop:

    grep -wvf ignore.txt /etc/passwd | awk -F: -v OFS=: '{print $1, $2, $3}'
  • echo $(date) is pointless. Just use date.

  • Use tee to write to a file and again to the pipe:

    ) | tee "$(hostname)"_userlogins.txt | mail ...

Overall, the script can be simplified to:

#!/bin/sh
(
echo List of users in PRD 

date

grep -wvf ignore.txt /etc/passwd | awk -F: -v OFS=: '{print $1,$3,$5}' | sort 
) | tee "$(hostname)"_userlogins.txt |
mailx -s file [email protected]
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11
  • i tried above,i didnt get any output other than list of users in Prd and date,am i missing something? Commented Apr 24, 2015 at 3:47
  • 1
    @ZairaZareena does your ignore.txt contain a blank line? Commented Apr 24, 2015 at 3:48
  • its just has username like Commented Apr 24, 2015 at 3:51
  • it worked like a charm thank you only problem i have is there is no gap between them (between list of prd, date and the username list) Commented Apr 24, 2015 at 3:57
  • @ZairaZareena add an echo command wherever you need a gap - without any arguments,echo just prints a blank line. Commented Apr 24, 2015 at 3:58

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