Linux System Administration

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Appendix

APPENDIX

bash Script Samples

This appendix contains several scripts that can be useful to you in your daily work,

as well as serving as models for writing other scripts. You can download the scripts

from http://www.centralsoft.org.

Adding Users

If you have a lot of turnover (such as in a university, where new students enter in

bunches once or several times a year), this script can help you add them to your sys-

tem quickly. It reads a file listing information about each user and invokes useradd

with the proper arguments (see the section “User Management” in Chapter 8 for

details about useradd and its variants):

#!/bin/bash

expiredate=2009-02-18

if [[ -z "$1" ]] ; then

echo ""

echo "Please give exactly one file name."

echo "The file will have one user per line."

echo "Each line will have:"

echo " username"

echo " group"

echo " personal real name"

echo ""

echo "Sample line:

echo "alfredo marketing Alfredo de Darc"

exit 1

fi

cat "$1" | while read username groupname realname

do

# Skip blank lines.

if [[ -z $username || -z $groupname || -z $realname ]]; then

continue

fi