Shell Programming and Scripting

#!/usr/bin/bash
cat /etc/passwd | while read A
do
USER=`echo “$A” | cut -f 1 -d “:”`
echo “Found $USER”
done


This shell script should make USER = the first field of the first line of the file /etc/passwd
Eg:
adm
daemon
bob
jane
kev
etc ...

However USER=echo “$A” | cut -f 1 -d “:”
What have I done wrong ???

Thanks

That should work...

If USER equals the literal string echo “$A” | cut -f 1 -d “:” then I'd guess you're actually using single quotes inside your loop.

E.G:

Code:

USER='echo “$A” | cut -f 1 -d “:”'

instead of

Code:

USER=`echo “$A” | cut -f 1 -d “:”`

This would be much easier done using awk.

USER=`awk -F: '{print $1}' /etc/passwd | grep $A`

google, where does $A get it's value in your script? Or do you mean that it should be used inside the loop? If it is, then you're doing a ton more work reading the file again in each iteration of the loop..

kevin, if all you want to do is display the names, part of google's script will work for you with a small addition:

Code:

awk -F: '{print "Found " $1}' /etc/passwd

If you want to operate on each name, you could use this:

Code:

#!/usr/bin/bash
while read A
do
  USER=`echo “$A” | cut -f 1 -d “:”`
  echo “Found $USER”
done < /etc/passwd

But I still think your initital problem was using single quotes by mistake...