What's the easiest way to get a user's full name on a Linux/POSIX system?

Question

I could grep through /etc/passwd but that seems onerous. \'finger\' isn\'t installed and I\'d like to avoid that dependency. This is for a program so it would be nice if there

Answer 1

On a modern glibc system, use this command:

getent passwd "username" | cut -d ':' -f 5

That'll get you the passwd entry of the specified user, independent of the underlying NSS module.

Read the manpage of getent.

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If you're already programming, you can use the getpwnam() C-Function:

struct passwd *getpwnam(const char *name);

The passwd struct has a pw_gecos member which should contain the full name of the user.

Read the manpage of getpwnam().

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Be aware that many systems use this field for more than the full name of the user. The most common convention is to use a comma (,) as separator within the field and place the users real name first.

Answer 2

Take 1:

$ user_name=sshd
$ awk -F: "\$1 == \"$user_name\" { print \$5 }" /etc/passwd
Secure Shell Daemon

However, passwd database supports special character '&' in the gecos, which should replaced with capitalized value of user name:

$ user_name=operator
$ awk -F: "\$1 == \"$user_name\" { print \$5 }" /etc/passwd
System &

Most of answers here (except for finger solution) do not respect &. If you want to support this case, then you'll need a more complicated script.

Take 2:

$ user_name=operator
$ awk -F: "\$1 == \"$user_name\" { u=\$1; sub(/./, toupper(substr(u,1,1)), u);
    gsub(/&/, u, \$5); print \$5 }" /etc/passwd
System Operator

Answer 3

My code works in bash and ksh, but not dash or old Bourne shell. It reads the other fields too, in case you might want them.

IFS=: read user x uid gid gecos hm sh < <( getent passwd $USER )
name=${gecos%%,*}
echo "$name"

You could also scan the whole /etc/passwd file. This works in plain Bourne shell, in 1 process, but not so much with LDAP or what.

while IFS=: read user x uid gid gecos hm sh; do
  name=${gecos%%,*}
  [ $uid -ge 1000 -a $uid -lt 60000 ] && echo "$name"
done < /etc/passwd

On the other hand, using tools is good. And C is good too.

Answer 4

The way that I figured it on Linux to get the full name into a variable was:

u_id=`id -u`
uname=`awk -F: -vid=$u_id '{if ($3 == id) print $5}' /etc/passwd`

Then just simple use the variable, ex: $ echo $uname