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.

2013年8月7日 · How to tell if a string is not defined in a Bash shell script. See more linked questions. Related. 3222.

2021年10月27日 · 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.

2016年5月24日 · BTW, next time you have some shell you don't understand, try copying-and-pasting it into explainshell.com (albeit, in this case, either without the if, or adding a ; then : "something here"; fi at the end to make the syntax correct).

2024年12月14日 · Bash shell: Bash shell stands for Bourne Again Shell. Bash shell is the default shell in most Linux distributions and substitute for the Sh shell (the Sh shell will also run in the Bash shell). The Bash shell can execute the vast majority of Sh shell scripts without modification and provide commands line editing feature also.

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 non-zero return status means failure.

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.

(From the Bash man page: "Any part of the pattern may be quoted to force it to be matched as a string."). Here in Bash, the two statements yielding "yes" are pattern matching, other three are string equality:

2013年11月19日 · Every command you run from the shell reports a numeric status back to the shell when it finishes running; in general, a value of 0 means the command succeeded, and a nonzero value means it failed. (That seems backward, but the idea is that there's usually only one way to succeed but potentially lots of ways things can go wrong.

2013年10月18日 · [ ] is actually a shell built-in command, which, can actually be implemented as an external command. Look at your /usr/bin, there is most likely a program called "[" there! Strictly speaking, [ ] is not part of bash syntax. [[ ]] is a shell keyword, which means it is part of shell syntax. Inside this construct, some reserved characters change ...