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
Just in case you want to do this from C, try something like this:
#include <sys/types.h>
#include <pwd.h>
#include <errno.h>
#include <stdio.h>
#include <string.h>
/* Get full name of a user, given their username. Return 0 for not found,
-1 for error, or 1 for success. Copy name to `fullname`, but only up
to max-1 chars (max includes trailing '\0'). Note that if the GECOS
field contains commas, only up to to (but not including) the first comma
is copied, since the commas are a convention to add more than just the
name into the field, e.g., room number, phone number, etc. */
static int getfullname(const char *username, char *fullname, size_t max)
{
struct passwd *p;
size_t n;
errno = 0;
p = getpwnam(username);
if (p == NULL && errno == 0)
return 0;
if (p == NULL)
return -1;
if (max == 0)
return 1;
n = strcspn(p->pw_gecos, ",");
if (n > max - 1)
n = max - 1;
memcpy(fullname, p->pw_gecos, n);
fullname[n] = '\0';
return 1;
}
int main(int argc, char **argv)
{
int i;
int ret;
char fullname[1024];
for (i = 1; i < argc; ++i) {
ret = getfullname(argv[i], fullname, sizeof fullname);
if (ret == -1)
printf("ERROR: %s: %s\n", argv[i], strerror(errno));
else if (ret == 0)
printf("UNKONWN: %s\n", argv[i]);
else
printf("%s: %s\n", argv[i], fullname);
}
return 0;
}
You don't specify a programming language, so I'll assume you want to use the shell; here's an answer for Posix shells.
Two steps to this: get the appropriate record, then get the field you want from that record.
First, getting the account record is done by querying the passwd
table:
$ user_name=foo
$ user_record="$(getent passwd $user_name)"
$ echo "$user_record"
foo:x:1023:1025:Fred Nurk,,,:/home/foo:/bin/bash
For hysterical raisins, the full name of the user is recorded in a field called the “GECOS” field; to complicate matters, this field often has its own structure with the full name as just one of several optional sub-fields. So anything that wants to get the full name from the account record needs to parse both these levels.
$ user_record="$(getent passwd $user_name)"
$ user_gecos_field="$(echo "$user_record" | cut -d ':' -f 5)"
$ user_full_name="$(echo "$user_gecos_field" | cut -d ',' -f 1)"
$ echo "$user_full_name"
Fred Nurk
Your programming language probably has a library function to do this in fewer steps. In C, you'd use the ‘getpwnam’ function and then parse the GECOS field.
Combination of other answers, tested on minimal Debian/Ubuntu installations:
getent passwd `whoami` | cut -d ':' -f 5 | cut -d ',' -f 1
The good old finger may also help :-)
finger $USER |head -n1 |cut -d : -f3
Try this:
getent passwd eutl420 | awk -F':' '{gsub(",", "",$5); print $5}'
The top two answers can be combined in one line:
getent passwd <username> | cut -d ':' -f 5 | cut -d ',' -f 1