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- bash - What are the special dollar sign shell variables . . . - Stack . . .
In Bash, there appear to be several variables which hold special, consistently-meaning values For instance, myprogram amp;; echo $! will return the PID of the process which backgrounded myprog
- shell - Bash regex =~ operator - Stack Overflow
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 left side? The right side is considered an extended regular expression If the left side matches, the operator returns 0, and 1 otherwise Why are double square brackets required when running a test? Because =~ is an operator of
- bash - What is the purpose of in a shell command? - Stack Overflow
$ 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 only found in Bash It intends to prevent the running of the second process if the first fails You may notice I've used the word "intent" - that's for good reason
- linux - What does $@ mean in a shell script? - Stack Overflow
What does a dollar sign followed by an at-sign (@) mean in a shell script? For example: umbrella_corp_options $@
- bash - Shell equality operators (=, ==, -eq) - Stack Overflow
Bash variables are so [[ "yes" -eq "no" ]] is equivalent to [[ "yes" -eq 0 ]] or [[ "yes" -eq "any_noninteger_string" ]] -- All True The -eq forces integer comparison
- Whats the difference between lt; lt;, lt; lt; lt; and lt; lt; in bash?
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 whenever that delimiter is seen, the program will read all the stuff you've given to the program as input and perform a task upon it Here's what I mean: $ wc << EOF > one two three > four five > EOF 2 5 24 In this example we
- bash - What does lt; lt; lt; mean? - Unix Linux Stack Exchange
Take a look at the Bash man page This notation is part of what's called a here documents here strings It allows you the ability to generate multi-line data input as one continuous string The variation you're asking about is called a here string excerpt from Bash man page Here Strings A variant of here documents, the format is: <<<word The word is expanded and supplied to the command on
- An and operator for an if statement in Bash - Stack Overflow
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 compliant, stay away from it; otherwise, it's basically down to personal preference
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