Creating a User with Access to a Single Command

[Ariel Biener]

That's not what you want. Please read about "restricted shell".

A working example:

/etc/passwd:
ariel:x:uid:gid::/home/ariel:/bin/rbash

ls -l /bin/rbash
lrwxrwxrwx  1 root root 4 Apr 10  2006 /bin/rbash -> bash

drwx-----t  4 ariel mygroup 4096 Apr  1 22:50 /home/ariel

ls -al ~ariel
-r-xr-xr-x    1 root  root   688 Apr  7  2010 .profile
-rw-r--r--    1 root  root     0 Apr  7  2010 .inputrc
lrwxrwxrwx    1 root  root     8 Apr  7  2010 .bashrc -> .profile
lrwxrwxrwx    1 root  root     8 Apr  7  2010 .bash_profile -> .profile
-rw-r--r--    1 root  root     0 Apr  7  2010 .bash_logout
lrwxrwxrwx    1 root  root     8 Apr  7  2010 .bash_login -> .profile
drwx------    2 ariel mygroup 4096 Apr 23  2010 .ssh
-rw-------    1 ariel mygroup 660 Apr  1 22:50 .Xauthority

cat .profile
#! /bin/rbash

declare -r PS1='(myhost)>'

unset BASH_VERSION
unset HISTFILE
unset HISTFILESIZE
unset HOSTTYPE
unset MACHTYPE
unset OSTYPE
unset _INIT_PREV_LEVEL
unset _INIT_RUN_LEVEL
unset _INIT_RUN_NPREV
unset _INIT_UTS_ISA
unset _INIT_UTS_MACHINE
unset _INIT_UTS_NODENAME
unset _INIT_UTS_PLATFORM
unset _INIT_UTS_RELEASE
unset _INIT_UTS_SYSNAME
unset _INIT_UTS_VERSION

unset PATH
unset MAIL
unset MAILCHECK
unset HISTFILESIZE
unset HISTSIZE
unset HZ
unset PS2
unset PS4

declare -rx PATH=/usr/local/restricted
declare -rx HOSTNAME=myhost.mydomain
declare -rx TZ=Israel

echo "
Welcome to gate.

The following commands can be used: telnet, ssh.
"

declare -rx HOME=~
=========================

ls -l /usr/local/restricted
lrwxrwxrwx  1 root root 12 Apr 10  2006 ssh -> /usr/bin/ssh
lrwxrwxrwx  1 root root 24 Mar 13  2006 telnet -> /usr/kerberos/bin/telnet

-- Ariel
 --
 Ariel Biener
 e-mail: ariel at post.tau.ac.il
 PGP: http://www.tau.ac.il/~ariel/pgp.html