Category: 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.

Debian releases and names

Debian releases are named after characters from Toy Story and are frequently referred to with the name rather than the version. This post is for my own quick reference for the version-to-name of each Debian release.

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Showing seconds with ls on Linux and OSX

Using the "ls" command to list directory contents from the command line with the -l flag will include the date and time down to the minute, but not show the seconds. This post shows how to display the seconds as well with bash on Linux and OSX.

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Show only one process with top on Linux

Top is a useful command line tool for showing processes running on Linux such as how much CPU and memory they've been using and how long they've been running, and also showing the system load, CPU and memory usage as a whole. But what if you only one to show output for one process or command?

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Change the commit message with git

I'm sure you've done it before: added a commit message with git but typed it in wrong and need to change it. If you haven't pushed the commit yet then it's as simple as 'git commit –amend -m "New commit message"'.

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Install Java on the command line with Debian

If it was nice and intuitive to install Java on Debian (and other Debian based distros such as Ubuntu), I wouldn’t need to write this post because it would just be "apt-get install java". But no, I always forget what I need to install, hence this post…

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Setting a user’s supplementary groups on Linux

A user on Linux belongs to a primary group, which is specified in the /etc/passwd file, and can be assigned to multiple supplementary groups, which are specific in the /etc/group file. The usermod command can be used after creating to user to assign them to additional groups(s).

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List directories only with ls

The ls command is used to list directory contents when using the bash shell (and other shells), and has a variety of flags to choose what to display and how to format. This post shows how to list just the directories using ls.

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