Why does the output differ when executed from a shell script?

Question

According to this post, I run this from the command line:

USER_HOME=$(getent passwd $SUDO_USER | cut -d: -f6)

and get the following output:

/root
/usr/sbin
/bin
/dev
/bin
/usr/games
/var/cache/man
/var/spool/lpd
/var/mail
/var/spool/news
/var/spool/uucp
/bin
/var/www
/var/backups
/var/list
/var/run/ircd
/var/lib/gnats
/nonexistent
/var/lib/libuuid
/home/user
/var/run/vboxadd
/var/lib/puppet
/var/run/sshd

When I run this in a script (as sudo, which is the point of the whole thing --- as sudo, ~ expands to /root):

USER_HOME=$(getent passwd $SUDO_USER | cut -d: -f6)
echo $USER_HOME

I get my correct path /home/user.

Why can I not invoke my function manually to get the same output?

This is probably better asked over at unix.stackexchange.com — Michael Berkowski
– Michael Berkowski, Commented Jan 11, 2014 at 20:58
This command is designed to run by sudo. How are you running it from the command line? — n. m. could be an AI
– n. m. could be an AI, Commented Jan 11, 2014 at 21:01
I don't understand. When I run getent passwd user | cut -d: -f6 as an ordinary for any value of user, I just get the user's home directory, not all of the stuff you cited. What is the value of $SUDO_USER? — Andrew Schulman
– Andrew Schulman, Commented Jan 11, 2014 at 21:08

damienfrancois · Accepted Answer · 2014-01-11 21:24:07Z

5

Because when not using sudo, $SUDO_USER is not set and you get the output of getent passwd without further argument, which lists all users. The cut then extracts the home directory part.

Replace $SUDO_USER with $USER when not running with sudo.

Note that using getent passwd ${SUDO_USER:-$USER} should work in both cases.

answered Jan 11, 2014 at 21:24

damienfrancois

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