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- linux - What does $@ mean in a shell script? - Stack Overflow
The shell splits tokens based on the contents of the IFS environment variable Its default value is \t\n; i e , whitespace, tab, and newline Expanding "$@" gives you a pristine copy of the arguments passed Expanding $@ may not
- What is the $? (dollar question mark) variable in shell scripting?
The shell treats several parameters specially These parameters may only be referenced; assignment to them is not allowed [ ]? Expands to the exit status of the most recently executed foreground pipeline ANSI C and POSIX then recommend that: 0 means the program was successful other values: the program failed somehow
- Difference between $ {} and $ () in a shell script - Super User
The above (along with many more forms of ${parameter…something_else} constructs) are discussed at greater length in the shell’s man page, bash(1) A Note on Quotes Note that you should always quote shell variables unless you have a good reason not to, and you’re sure you know what you’re doing By contrast, while braces can be
- What is the meaning of $? in a shell script? - linux
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 encourages the use of "positive logic", the practice of writing conditionals without negations, which has cognitive simplicity in most situations
- bash - Shell equality operators (=, ==, -eq) - Stack Overflow
What is the difference between =, == and -eq in shell scripting? Is there any difference between the following?
- shell - Difference between sh and Bash - Stack Overflow
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, Bash, C shell, Z shell, etc Using any of the shell programs, we will be able to execute commands that are supported by that shell program Bash - It derived from Bourne
- bash - 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, and not only found in Bash It intends to prevent the running of the second process if the first fails
- shell - How to concatenate string variables in Bash - Stack Overflow
A bashism is a shell feature which is only supported in bash and certain other more advanced shells It will not work under busybox sh or dash (which is bin sh on a lot of distros), or certain other shells like the bin sh provided on FreeBSD –
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