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up vote 2 down vote favorite

new to bash scripting so just wondering if i am doing this code right at all. im trying to search /etc/passwd and then grep and print users.

usage ()
{
     echo      "usage: ./file.sk user"
}
# test if we have two arguments on the command line
if [ $# != 1 ]
then
    usage
    exit
fi

if [[ $# < 0 ]];then
   usage
   exit
fi

# Search for user
fullname=`grep $1 /etc/passwd | cut -f 5 -d :`
firstname=`grep $1 /etc/passwd | cut -f 5 -d : | cut -f 1 -d " "`

#check if there. if name is founf: print msg and line entry
not sure as how to this or if im doing this right...

am i doing this right?

share|improve this question
Your second $# test is redundant, if the code reaches it $# must be 1. – Kevin Jan 16 '12 at 19:06
And have a look at the finger command. – Kevin Jan 16 '12 at 19:10
Unquoted < is redirection, not numeric comparison. As others have pointed out, the condition is redundant anyway, but this error could be pretty hard to debug, so I'm pointing it out separately. – tripleee Jan 16 '12 at 19:59

5 Answers

up vote 0 down vote

You can simply by reading your input to an array and then printing out your desired fields, something like this -

grep $1 /etc/passwd | while IFS=: read -a arry; do 
    echo ${arry[0]}:${arry[4]}; 
done

Test:

jaypal:~/Temp] echo "root:*:0:0:System Administrator:/var/root:/bin/sh" | 
while IFS=: read -a arry; do 
    echo ${arry[0]}:${arry[4]}; 
done
root:System Administrator
share|improve this answer
up vote 3 down vote 
grep $1 /etc/passwd | while IFS=: read -r username passwd uid gid info home shell
do
  echo $username: $info
done
share|improve this answer
up vote 1 down vote

Instead of this:

fullname=`grep $1 /etc/passwd | cut -f 5 -d :`
firstname=`grep $1 /etc/passwd | cut -f 5 -d : | cut -f 1 -d " "`

Try this:

fullname=$(cut -f5 -d: /etc/passwd | grep "$1")

if [[ $? -ne 0 ]]; then
    # not found, do something
fi

firstname=${fullname%% *} # remove the space and everything after

Note that I changed my answer to cut before grep so that it doesn't get false positives if some other field matches the full name you are searching for.

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Thanks for pointing that out--I'll fix my answer. – John Zwinck Jan 16 '12 at 19:19
That's OK, I'll update my answer again, but in the meantime I made some improvements, so thanks anyway! – John Zwinck Jan 16 '12 at 19:25
up vote 2 down vote

This might work for you:

fullname=$(awk -F: '/'$1'/{print $5}' /etc/passwd)
firstname=${fullname/ *}
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up vote 1 down vote

You're on the right track.

But I think the 2nd if [[ $# < 0 ]] .... fi block doesn't get you much. Your first test case gets the situation right, 'This script requires 1 argument or quits'.

Also, I don't see what you need firstname for, so a basic test is

 case "${fullname:--1}" in 
   -[1] ) printf "No userID found for input=$1\n" ; exit 1 ;;
   * )
     # assume it is OK
     # do what every you want after this case block
   ;;
 esac

You can of course, duplicate this using "${firstname}" if you really need the check.

OR as an equivalent if ... fi is

 if [[ "${fullname}" == "" ]] ; then
    printf "No userID found for input=$1\n" ; exit 1
 fi

note to be more efficient, you can parse ${fullname} to get firstname without all the calls to grep etc, i.e.

 firstname=${fullname%% *}

Let me know if you need for me to explain :--1} and %% *} variable modifiers.

I hope this helps.

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