bash - What are the special dollar sign shell variables ... - Stack ...
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 …
How do AND and OR operators work in Bash? - Stack Overflow
How do AND and OR operators work in Bash? Asked 13 years ago Modified 2 years, 9 months ago Viewed 22k times
bash - What is the purpose of "&&" in a shell command? - Stack …
Dec 22, 2010 · In shell, when you see $ 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 …
bash - Shell equality operators (=, ==, -eq) - Stack Overflow
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 …
What does $# mean in bash? - Ask Ubuntu
Jul 25, 2017 · Furthermore, when you use bash -c, behavior is different than if you run an executable shell script, because in the latter case the argument with index 0 is the shell …
What does 'set -e' mean in a Bash script? - Stack Overflow
By default, Bash does not do this. This default behavior is exactly what you want if you are using Bash on the command line you don't want a typo to log you out! But in a script, you really want …
shell - Bash regex =~ operator - Stack Overflow
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 …
Meaning of $? (dollar question mark) in shell scripts
Aug 1, 2019 · What does echo $? mean in shell programming? true echo $? # echoes 0 false echo $? # echoes 1 From the manual: (acessible by calling man bash in your shell) ? Expands …
What's the difference between <<, <<< and < < in bash?
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 …
What does the -e do in a bash shebang? - Unix & Linux Stack …
All the bash command line switches are documented in man bash. -e Exit immediately if a pipeline (which may consist of a single simple command), a subshell command enclosed in …