linux - What does $@ mean in a shell script? - Stack Overflow
2012年4月3日 · The shell splits tokens based on the contents of the IFS environment variable. Its default value is \t\n; i.e., whitespace, tab, and newline. Expanding "$@" gives you a pristine copy of the arguments passed. Expanding $@ may not.
regex - Meaning of "=~" operator in shell script - Stack Overflow
2012年9月17日 · The return value is 0 if the string matches the pattern, and 1 otherwise. If the regular expression is syntactically incorrect, the conditional expression's return value is 2. If the shell option nocasematch is enabled, the match is performed without regard to the case of alphabetic characters.
What is the $? (dollar question mark) variable in shell scripting?
Try the following in the shell: ls somefile echo $? If somefile exists (regardless whether it is a file or directory), you will get the return value thrown by the ls command, which should be 0 (default "success" return value). If it doesn't exist, you should get a number other then 0. The exact number depends on the program.
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 ...
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
2024年12月14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, 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 ...
What are the special dollar sign shell variables? - Stack Overflow
2012年9月14日 · $0 is the name of the shell or shell script. Most of the above can be found under Special Parameters in the Bash Reference Manual. Here are all the environment variables set by the shell. For a comprehensive index, please see the Reference Manual Variable Index.
Increment variable value by 1 (shell programming)
I can't seem to be able to increase the variable value by 1. I have looked at tutorialspoint's Unix / Linux Shell Programming tutorial but it only shows how to add together two variables. I have tried the following methods but they don't work:
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 even go so far as: I suppose you could even go so far as:
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 encourages the use of "positive logic", the practice of writing conditionals without negations, which has cognitive simplicity in most situations.