Linux/Unix/BSD

Information And Reviews On Linux, Unix And Bsd Operating Systems

Unix is a multi-user, multi-tasking operating system that was initially developed by Bell Labs in the 1970s. Various similar operating systems that are POSIX compliant (ie compatible with Unix) have since been developed (POSIX is an abbreviation for Portable Operating System Interface for UNIX). These include the following: the BSD family (OpenBSD, FreeBSD, NetBSD, Mac OS/X), Solaris, IRIX, AIX, SunOS, UnixWare, OpenServer and Linux.

Software written for POSIX compliant operating systems is generally able to be compiled for all POSIX platforms with little or no platform-specific changes. This makes the commands and utilities available for this extended family of operating systems very similar, and there are few differences between administering them.

The articles in this section are about useful command line utilities and commonly used application software on POSIX compliant operating systems. For Mac OSX specific articles see my OSX section.

Howto Mount an ISO Image with FreeBSD

If you have created an ISO image with a utility like mkisofs or have downloaded an ISO image from a website or FTP archive you can mount it on your filesystem without having to burn it to CD or DVD first. Doing this in Linux is fairly straight forward but it’s a two step process in FreeBSD.

Please note that these instructions are no longer valid for recent releases of FreeBSD because vnconfig is no longer supported. Thanks to Leif Neland for letting me know about this.

Thanks to Rollin Kibbe for supplying updated information available here.

Say for example you are wanting to mount a CD ISO image of a Linux distribution such as Fedora Core 3 Disc 1; the filename of the ISO file in this example is FC3-i386-disc1.iso This example assumes you are in the same directory as the ISO image and that the mount point (/cdrom in this example) already exists.

Mounting the ISO Image

vnconfig /dev/vn0c ./FC3-i386-disc1.iso mount -t cd9660 /dev/vn0c /cdrom

The above mounts the CD-ROM filesystem at /cdrom and doing ls -l /cdrom will show the contents of the root level of the CD.

Unmounting the ISO Image

umount /cdrom vnconfig -u /dev/vn0c

It is likely you will need to be the root user to issue these commands. You can either do this by su‘ing to root or by using the sudo command like so:

sudo -u root vnconfig /dev/vn0c ./FC3-i386-disc1.iso sudo -u root mount -t cd9660 /dev/vn0c /cdrom

sudo -u root umount /cdrom sudo -u root vnconfig -u /dev/vn0c

Modifying the Linux Grub boot loader’s options

One of my Linux CD Mall customers emailed me the other day with a Linux annoyance: "The computer always booted into Linux by default if I wasn’t quick enough to stop it. Most annoying. I would have preferred the computer to wait until I told it where to boot but could not find a way of doing that. All of the Linux distros that I tried just take over without being asked." This post looks at how you can change the grub boot loader’s settings to solve this issue using a text editor. And I agree with him, it is annoying how the boot loader is often set up by default to boot into Linux too quickly.

Man Pages – Manpage for chmod

Man page for the unix linux bsd command chmod. NAME SYNOPSIS DESCRIPTION STICKY FILES STICKY DIRECTORIES OPTIONS AUTHOR REPORTING BUGS COPYRIGHT SEE ALSO NAME chmod – change file access permissions SYNOPSIS chmod [OPTION]… MODE[,MODE]… FILE… chmod [OPTION]… OCTAL-MODE FILE… chmod [OPTION]… –reference=RFILE FILE… DESCRIPTION This manual page documents the GNU version of chmod. chmod changes …

PageUp and PageDown history search auto completion on the BASH shell

From the BASH shell it’s possible to have auto-completion where you start to type in part of a command, and then use a keystroke sequence, such as PageUp or PageDown, to then cycle through the history for commands which started with the first text you have entered.

Changing the hostname on CentOS

If the hostname setting is incorrect on your CentOS/RedHat/Fedora machine, it’s really easy to change the hostname from the command line. There are also GUI tools for doing this but we’ll just look at the CLI tools for doing this.

Install Yum on openSUSE with Yast

openSUSE has an excellent system management tool called Yast, but the software package management tool in Yast is really slow to run. It is possible to install and use Yum instead on openSUSE and all of a sudden the slowness of running Yast’s package management goes away. I have a pretty fast machine with a lot of memory, but it can take 5 to 10 minutes to open up the Yast software management application.