How to get the logged in user's real name in Unix?

Question

I'm looking to find out the logged in user's real (full name) to avoid having to prompt them for it in an app I'm building. I see the finger command will output a columned list of data that includes this and was wondering if it makes sense to grep through this or is there an easier way? None of the switches for finger that I've found output just the real name. Any thoughts would be much appreciated.

Answer 1

getent passwd `whoami` | cut -d : -f 5

(getent is usually preferable to grepping /etc/passwd).

Answer 2

getent passwd "$USER" | cut -d: -f5 | cut -d, -f1

This first fetches the current user's line from the passwd database (which might also be stored on NIS or LDAP)

In the fetched line, fields are separated by : delimiters. The GECOS entry is the 5th field, thus the first cut extracts that.

The GECOS entry itself is possibly composed of multiple items - separated by , - of which the full name is the first item. That's what the second cut extracts. This also works if the GECOS entry is lacking the commas. In that case the whole entry is the first item.

You can also assign the result to a variable:

fullname=$( getent passwd "$USER" | cut -d: -f5 | cut -d, -f1 )

Or process it further directly:

echo "$( getent passwd "$USER" | cut -d: -f5 | cut -d, -f1 )'s home is $HOME."

cat <<EOF
Hello, $( getent passwd "$USER" | cut -d: -f5 | cut -d, -f1 ).
How are you doing?
EOF

Answer 3

You can use getpwent() to get each successive password entry until you find the one that matches the currently logged in user, then parse the gecos field.

Better, you can use getpwuid() to directly get the entry for the uid of the current user.

In either case,

1. You have to first get the current user's login name or id, and
2. There is no guarantee that the gecos field actually contains the user's real full name, or anything at all.