Sometimes when I type a command in bash, I mistakenly type in the \ character at the end, as it is close to the Enter key. Whenever I do this, I get a prompt on the next line, like this:
>_
The same output is produced when the ` character is used.
What exactly does this \ do to the command?
Are there other characters (besides \ and `) that give a similar output?
the \ character allows you to break your command into multiple lines :
$ grep "hello" /tmp/file
is equivalent to :
$ grep "hello" \
> /tmp/file
the ' and " character allows you to define multiline strings, and the ` is a way to use the output of a command as an argument to another. $(command) does the same thing.
whenever you see
>
it means that the command syntax is not complete. Some shell constructs also needs to be terminated, like while, for, if ...
The displayed > can be configured with the PS2 environnement variable.
as requested, here is an example using ` :
suppose i have a list of files into filelist.txt:
$ cat filelist.txt
a.c
a.h
Makefile
test.cfg
[...]
i want to know the number of lines in each of those files. the command would be wc -l a.c a.h Makefile [...]. to use the output of the cat filelist.txt as arguments to wc -l, i can use :
$ wc -l `
> cat filelist.txt
> `
\ is the line continuation character. When at the end of a line, the next line is considered a continuation of the current line.
` is a backtick. Backticks come in pairs, and bash allows contained newlines in pretty much any of the quotes/brackets. You'll see similar (line continuation) behavior with " and ' as well as () and {}.