You can find a very nice reference for bash's [ aka test builtin's operators here, or by running help test in a bash shell or info bash test or info bash '[' from any shell¹. If you are using a different shell, just search for the description of its [ or test builtin in its documentation of if it doesn't have such a builtin², in the man page of the standalone test utility³ and you will find ...

2016年7月20日 · This is good, but, in my opinion, you'd do a lot better to read and understand the POSIX spec rather than the bash scripting guide, or whatever. In the main, the information available at links like that is lacking in important ways. Anyway, thus misses two crucial points concerning shell splitting - globbing and IFS whitespace.

This worked for me. When using a bash script to composite a string that gets automatically copied onto the clipboard for subsequent pasting elsewhere, this approach worked for adding newlines in the resulting output.

2017年6月17日 · If you came here wondering what bash -n myscript does, it does a syntax check on the script instead of running it.

The third line is outputted by the n command in the script. The fourth line is outputted three times, twice by the two p in the script after n has read the next line, and once by the default p command.

2023年10月2日 · I want to run a bash script every N seconds, where even if it fails, I want while loop to continue without crashing. I am using the following solution How to repeatedly run bash script every N seco...

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2021年6月16日 · I am using echo to debug my shell script and would like to know how to use echo to also print out the new line \n and/or carriage return \r characters as well in the form \n and \r in order to inspect strings. Is this possible?

2016年12月6日 · I want to write logic in shell script which will retry it to run again after 15 sec upto 5 times based on "status code=FAIL" if it fails due to some issue.

2017年6月14日 · You are given -n and -z for the same reason that other test suites give you both == and !=, or AND and NOT. Some test cases can be made a lot clearer to future maintainers by eschewing double-negatives. Also, as mentioned in an above comment, ancient incarnations of sh (i. e. the Bourne and Thompson shells), as opposed to modern POSIX sh did not have a ! keyword to negate the truthiness of ...