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.

2015年9月27日 · In bash these are implemented via temp files, usually in the form /tmp/sh-thd.<random string>, while in dash they are implemented as anonymous pipes. This can be observed via tracing system calls with strace command. Replace bash with sh to see how /bin/sh performs this redirection. $ strace -e open,dup2,pipe,write -f bash -c 'cat <<EOF > test ...

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.

This is not the case with Bash, however, in which both operators have the same precedence, which is why Bash parses your expression using the left-associativity rule. Thanks to Kevin's comment for bringing this up. There might also be cases where all 3 expressions are evaluated.

Take a look at the Bash man page. This notation is part of what's called a here documents & here strings. It allows you the ability to generate multi-line data input as one continuous string. The variation you're asking about is called a here string. excerpt from Bash man page

2020年8月3日 · bash is a command interpreter, a shell, a program with an interface that interprets the commands that you put into it. When you call bash from bash, you simply start a new shell 'inside' the original shell. When you exit from this second shell, you return to the original shell.

All the bash command line switches are documented in man bash.-e Exit immediately if a pipeline (which may consist of a single simple command), a subshell command enclosed in parentheses, or one of the commands executed as part of a command list enclosed by braces (see SHELL GRAMMAR above) exits with a non-zero status.

The only reason why you'd want to use $? as arguments to a [command (whether that [command is run in the condition part of an if statement or not) is when you want to discriminate on a specific return status, like:

¹ Note you might have to install a info and/or bash-doc packages as some systems only supply manuals in man format by default (the information should also be in there even if harder to find). ² to find out if a command is available as a builtin, function, standalone external utility, you can use type in Bourne-like shells or fish , which in ...

2012年8月17日 · edit: have you tried sudo rm -r directoryName?The unwritten rules of the basic commands is that -r will allow a program to run recursively on every file your filesystem (starting where ever you choose!) and that -f will forcefully do things, even if it's dangerous. 'cd', 'mv', 'ls' mostly holds this principle true.