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.
I recently installed the VSFtpd FTP Server onto a CentOS box and have a fairly tight firewall setup script using iptables. When I logged in to test it and issued an "ls -l" command it took a really long time for the driectory listing to come back. At first I thought it wasn’t going to show the directory listing at all but it finally did. This post looks at the solution to the problem.
This quick tip shows how to find all the symbolic links under a particular directory using the “find” command from the command line on UNIX based systems such as Linux, OSX and BSD. Find all symbolic links Substitute [path] in the example below with the root level path you want to find symlinks from, and …
A little while ago I posted how to use the Linux/Unix/OSX find command to locate files bigger or smaller than a particular size but didn’t cover how to find zero length files. This is shown here.
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.
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.
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?