copy and paste this google map to your website or blog!
Press copy button and paste into your blog or website.
(Please switch to 'HTML' mode when posting into your blog. Examples: WordPress Example, Blogger Example)
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 - 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 with == as in C: $ (( 1==1 )); echo $? 0 $ (( 1==2 )); echo $? 1 (Note: 0 means true in the Unix sense and a failed test results in a non-zero number ) Using -eq inside of double parentheses is a syntax
Meaning of $? (dollar question mark) in shell scripts This is the exit status of the last executed command For example the command true always returns a status of 0 and false always returns a status of 1: true echo $? # echoes 0 false echo $? # echoes 1 From the manual: (acessible by calling man bash in your shell) ? Expands to the exit status of the most recently executed foreground pipeline By convention an exit status of 0 means success, and
How do AND and OR operators work in Bash? - Stack Overflow 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 thus only the left-hand side of the or runs, since that succeeds the right-hand side doesn't need to run
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
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
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
sh - [: missing `] in bash script - Stack Overflow The double-brace keyword is a bash expression, and will not work with other POSIX shells, but it has some benefits, as well, such as being able to do these kinds of operations more readably Of course, there are a lot of ways to test the number of arguments passed The mere existence of $2 will answer your question, as well