Sep 14, 2012 · In Bash, there appear to be several variables which hold special, consistently-meaning values. For instance, ./myprogram &; echo $! will return the PID of the process …

It depends on the Test Construct around the operator. Your options are double parentheses, double brackets, single brackets, or test. If you use ((…)), you are testing arithmetic equality …

May 22, 2025 · Single UNIX Specification- “The Standard” The Single UNIX Specification is the standard in which the core interfaces of a UNIX OS are measured. The UNIX standard …

I know that using ls -l "directory/directory/filename" tells me the permissions of a file. How do I do the same on a directory? I could obviously use ls -l on the directory higher in the hierarchy...

Sep 10, 2011 · When you try to execute a program in unix (one with the executable bit set), the operating system will look at the first few bytes of the file. These form the so-called "magic …

May 4, 2009 · First, if you look at the rm command man page (man rm under most Unix) you notice that –r means "remove the contents of directories recursively". So, doing rm -r . alone …

Jul 3, 2013 · a way to avoid the "grep -v grep" is to use "grep <process nam [e]>" so it interpolates the string and the process nam [e] isn't found when the first grep executes, if that makes sense.

I am trying to figure out what is the usage of this command: echo &lt; a.txt According to text book it should redirect a programs standards input. Now I am redirecting a.txt to echo but instead of

Jun 23, 2011 · The definition of unix time and the epoch date went through a couple of changes before stabilizing on what it is now. But it does not say why exactly 1/1/1970 was chosen in the …

Nov 9, 2012 · I have two directories with the same list of files. I need to compare all the files present in both the directories using the diff command. Is there a simple command line option …