原文：http://bash.cyberciti.biz/file-management/find-number-of-users-in-etcpasswd-file/
以下是该shell脚本的源代码：
#!/bin/bash
# Shell Script that outputs the number of users with entries in the
# Unix or Linux /etc/passwd file
# -------------------------------------------------------------------------
# Copyright (c) 2005 nixCraft project <http://cyberciti.biz/fb/>
# This script is licensed under GNU GPL version 2.0 or above
# -------------------------------------------------------------------------
# This script is part of nixCraft shell script collection (NSSC)
# Visit http://bash.cyberciti.biz/ for more information.
# -------------------------------------------------------------------------
PASSWD=/etc/passwd
# easy method with wc
OUT=$(wc -l $PASSWD)
# More accurate method to find out
# If user account suspended using # character then second method
# is more accurate and recommend
OUT1=$(grep -Ev "^#" $PASSWD | wc -l)
echo "$OUT [$OUT1]"
# You can filter result with awk
echo $OUT | awk '{ print $1 }' |