linux - What does $@ mean in a shell script? - Stack Overflow
2012年4月3日 · In brief, $@ expands to the arguments passed from the caller to a function or a script. Its meaning is context-dependent: Inside a function, it expands to the arguments …
regex - Meaning of "=~" operator in shell script - Stack Overflow
2012年9月17日 · An additional binary operator, =~, is available, with the same precedence as == and !=. When it is used, the string to the right of the operator is considered an extended …
bash - Shell equality operators (=, ==, -eq) - Stack Overflow
As a string operator, = is equivalent to ==. Also, note the whitespace around = or ==: it’s required. While you can do [[ 1 == 1 ]] or [[ $(( 1+1 )) == 2 ]] it is testing the string equality — not the …
Difference between $ {} and $ () in a shell script - Super User
76. $(command) is “command substitution”. As you seem to understand, it runs the command, captures its output, and inserts that into the command line that contains the $(…); e.g., …
What is the meaning of $? in a shell script? - linux
2011年2月20日 · This latter usage is faster, does not contaminate the shell's variable namespace with what amounts to temp variables, can often be a lot more readable for humans and …
What is the purpose of "&&" in a shell command? - Stack Overflow
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 shells, …
Meaning of $? (dollar question mark) in shell scripts
2019年8月1日 · 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 …
How to represent multiple conditions in a shell if statement?
2010年9月30日 · Indeed, if you read the 'portable shell' guidelines for the autoconf tool or related packages, this notation — using '||' and '&&' — is what they recommend. I suppose you could …
shell - Difference between sh and Bash - Stack Overflow
2021年10月25日 · Shell - "Shell" is a program, which facilitates the interaction between the user and the operating system (kernel). There are many shell implementations available, like sh, …
shell - What is the "eval" command in bash? - Unix & Linux Stack …
It's used to evaluate code dynamically. In shells, it's implemented as a shell builtin command. Basically, eval takes a string as argument and evaluates/interprets the code in it. In shells, …