have to determine all users home directories - tilde scripting problem

Question

Assume someuser has a home directory /home/someuser

NAME=someuser

In bash - what expression to I use combining tilde (~) and $NAME to return the users home d

Answer 1

BEST METHOD

Required: nothing (n.b., this is the same technique as getent without requiring getent)

home() { # returns empty string on invalid user
    grep "^$1:" /etc/passwd | cut -d ':' -f 6
}

# grep "^$user:" /etc/passwd | cut -d ':' -f 6
/var/lib/memcached

NICE METHOD FOR ROOT LINUX

Required: Linux, root (or sudo)

home() { # returns errorlevel 1 on invalid user
    su "$1" -s '/bin/sh' -c 'echo $HOME'
} 

# su memcached -s '/bin/sh' -c 'echo $HOME'
/var/lib/memcached

SOLUTION FOR COMPLETE EXPANSION

magic() { # returns unexpanded tilde express on invalid user
    local _safe_path; printf -v _safe_path "%q" "$1"
    eval "ln -sf $_safe_path /tmp/realpath.$$"
    readlink /tmp/realpath.$$
    rm -f /tmp/realpath.$$
}

Example usage:

$ magic ~nobody/would/look/here
/var/empty/would/look/here

$ magic ~invalid/this/will/not/expand
~invalid/this/will/not/expand

METHOD FOR HARNESSING CSH

This is a BASH script, it just calls csh.

Required: csh

home() { # return errorlevel 1 on invalid user
    export user=$1; csh -c "echo ~$user"
}

$ export user=root; csh -c "echo ~$user"
/var/root

$ export user=nodfsv; csh -c "echo ~$user"
Unknown user: nodfsv.

METHOD OF DESPERATION

Required: finger (deprecated)

home() {
    finger -m "$1" | 
    grep "^Directory:" | 
    sed -e 's/^Directory: //' -e 's/ .*//'
}

# finger -m "haldaemon" | 
> grep "^Directory:" | 
> sed -e 's/^Directory: //' -e 's/ .*//'
/home/haldaemon

You can combined the grep operation into sed, but since this method is sucky, I wouldn't bother.