getent.sh: The world's cheesiest getent implementation

getent

#!/bin/sh

# Copyright 2009 Rob Landley <rob at landley.net>, licensed under GPLv2.

isnum()
{
[ ! -z "$(echo $1 | grep '^[0-9]*$')" ]
}

nocomments()
{
sed 's/\([^#]*\)#.*/\1/' /etc/$1
}

# The world's cheesiest getent implementation

case "$1" in
passwd|group)
isnum "$2" &&
grep -m 1 "[^:]*:[^:]*:$2:" /etc/$1 ||
grep -m 1 "^$2:" /etc/$1
;;

hosts|networks|protocols)
nocomments $1 | grep -m 1 -w "$2"
;;

services)
nocomments $1 | (isnum "$2" && grep -m 1 "[ ]$2/" || grep -m 1 -w "$2")
;;
esac