#!/bin/bash

# This is the shell script to be constructed in Exercise 2
# of Module 3. Depending on the number of gid's at your site
# you made need to pipe the output of this script to 'more'
# or 'less'. My group is 100; you may need to use a
# different number.
#                             David Harrison, May 2002

echo -n "Number of users in group 100 (Method 1): "
cat /etc/passwd |
cut -d: -f4 |
grep '^100$' |  # We guard against matching say "1000"
wc -l

echo -n "Number of users in group 100 (Method 2): "
grep '^.*:.*:.*:100:' /etc/passwd | wc -l

# Put out a blank line so it looks nice on the screen.

echo

echo "All gids sorted by number (number gid):"

echo # Another blank line

cat /etc/passwd | # Putting each separate command on a
cut -d: -f4 |     # new line, as here, is usually considered
sort |            # to make the script more readable.
uniq -c |
sort -n

echo
echo "All gids sorted by gid (number gid): "
echo

cat /etc/passwd |
cut -d: -f4 |
sort |
uniq -c |
sort -n -k2

echo
echo "All gids sorted by gid (gid number):"
echo

cat /etc/passwd |
cut -d: -f4 |
sort |
uniq -c |
sort -n +1 | # This is equivalent to "sort -n -k2" above.
awk ' { print $2, $1 } '