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 …

Dec 22, 2010 · $ command one && command two the intent is to execute the command that follows the && only if the first command is successful. This is idiomatic of Posix shells, and not …

Oct 18, 2013 · What is the operator =~ called? I'm not sure it has a name. The bash documentation just calls it the =~ operator. Is it only used to compare the right side against the …

Apr 3, 2012 · What does a dollar sign followed by an at-sign (@) mean in a shell script? For example: umbrella_corp_options $@

Sep 27, 2015 · What's the difference between <<, <<< and < < in bash?Here document << is known as here-document structure. You let the program know what will be the ending text, and …

Modern shells such as Bash and Zsh have inherited this construct from Ksh, but it is not part of the POSIX specification. If you're in an environment where you have to be strictly POSIX …

8 In bash, && and || have equal precendence and associate to the left. See Section 3.2.3 in the manual for details. So, your example is parsed as $ (echo this || echo that) && echo other And …

Feb 10, 2010 · How do I compare a variable to a string (and do something if they match)?

Oct 10, 2010 · I reckon that the handle $@ in a shell script is an array of all arguments given to the script. Is this true? I ask because I normally use search engines to gather information, but I …