2012年9月14日 · In Bash, there appear to be several variables which hold special, consistently-meaning values. For instance, ./myprogram &; echo $! will return the PID of the process which backgrounded myprog...

The [[ ]] is treated specially by bash; consider that an augmented version of [ ] construct: [ ] 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 "[" …

2019年8月1日 · In Bash, when you hit enter, a fork + exec + wait happens like above, and bash then sets $? to the exit status of the forked process. Note: for built-in commands like echo, a process need not be spawned, and Bash just sets $? to 0 to simulate an external process. Standards and documentation

2010年10月10日 · Yes. Please see the man page of Bash (the first thing you go to) under Special Parameters:. Special Parameters. The shell treats several parameters specially.

2012年4月3日 · * Note: Word splitting. 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.

If not quoted, it is a pattern match! (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:

2017年1月27日 · help [[returns useful information—since [[an internal bash command—but does not say whether =~ uses basic or extended regex syntax. ⋯ The text you quoted is from the bash man page. I realize you said “read the bash man pages” but at first, I thought you meant read the man pages within bash.

In bash, && and || have equal precendence and associate to the left. See Section 3.2.3 in the manual for details. So, your example is parsed as $ (echo this || echo that) && echo other And thus only the left-hand side of the or runs, since that succeeds the right-hand side doesn't need to …

your understanding is right. For detailed info on {} see bash ref - parameter expansion 'for' and 'while' have different syntax and offer different styles of programmer control for an iteration. Most non-asm languages offer a similar syntax.

2017年7月25日 · Furthermore, when you use bash -c, behavior is different than if you run an executable shell script, because in the latter case the argument with index 0 is the shell command used to invoke it. As such, I think the way to fix this answer is to change it to execute scripts as files instead of using bash -c, since that's how the asker was doing it.