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Note: this method was developed for older CentOS / Redhat systems and is unlikely to be required now. Go to http://java.sun.com/ and download the JRE for your distribution. If your distro supports RPM packages, get the “Linux self extracting RPM” version. This will then create a .bin file, which you need to execute – ./.bin. […]

grep will find a specific string of text in a file, but awk gives you the ability to isolate a particular column of text. For example, we have a text file with the following content in a file called test.txt: This is a line of text demonstrating the use of awk. So, running the following […]

Anothe rmethod to perform a recursive find in Linux using xargs instead of -exec find -name ‘*.c’ | xargs ls “$1” – will give a directory listing of all files that end in .c Use find -iname for a case insensitive search.

How to use chmod in Linux. chmod u+ = assign user permissions chmod g+ = assign group permissions chmod a+ = assign all permissions Some examples: Command: chmod u+wrx testfile.txt Result: -rwx—— 1 root root 0 Feb 5 16:53 testfile.txt Command: chmod g+wrx testfile.txt Result: —-rwx— 1 root root 0 Feb 5 16:53 testfile.txt Command: […]

————————————————————————- HANDY ONE-LINERS FOR SED (Unix stream editor) Apr. 26, 2004 compiled by Eric Pement – pemente[at]northpark[dot]edu version 5.4 Latest version of this file is usually at: http://sed.sourceforge.net/sed1line.txt http://www.student.northpark.edu/pemente/sed/sed1line.txt This file is also available in Portuguese at: http://www.lrv.ufsc.br/wmaker/sed_ptBR.html FILE SPACING: # double space a file sed G # double space a file which already has […]

Postfix DEBUGGING 1.) If things are acting strangely here is a simple and quick first step that could save you a lot of time. * TO CHECK THE CURRENT CONFIGURATION: /usr/sbin/postfix check * validates the Postfix mail system configuration and will * warn about bad directory/file ownership or permissions, and * create missing directories. 2.) […]

dhcpd.conf netbios node types The following is a list of netbios node types, for the ISC dhcp server (should be pertinent to any DHCP server though). # These are the node types for netbios options: #1 = B-node, 2 = P-node, 4 =M-node, 8 = H-node option netbios-node-type 8; # default NetBIOS name resolution mode […]

DENY AND ALLOW USERS IN OPENSSH By default, OpenSSH allows logins for anyone with a valid password and shell. However, on a Linux system with numerous system accounts, this can be problematic. Imagine that you’re running a mail server, where each mail user has a system account. If you set up an e-mail account for […]

Create an iso image of a directory of files on Linux. mkisofs -J -R -v -T -o image.iso cdrom/ Will build an ISO image of all the files in the /cdrom directory.

Installing PERL modules perl -MCPAN -e “shell” Once in the shell: install Some::Module (in the above shell) or using MCPAN without the shell: perl -MCPAN -e “install ‘Some::Module'” or using cpan directly: cpan -i ‘Some::Module’