What does the =~ operator do?

Question

I have come across this operator =~ and couldn't figure it out on what it does. Could someone with bash knowledge kindly help me out?

http://stackoverflow.com/questions/218156/bash-regex-with-quotes — AGS, Nov 11 '14 at 00:48
Have you tried searching for it in the [bash documentation](http://linux.die.net/man/1/bash)? — Barmar, Nov 11 '14 at 00:51

score 2 · Answer 1 · answered Nov 11 '14 at 00:51

man bash

/=~

An additional binary operator, =~, is available, with the same precedence as == and !=. When it is used, the string to the right of the operator is considered an extended regular expression and matched accordingly (as in regex(3)). The return value is 0 if the string matches the pattern, and 1 otherwise. If the regular expression is syntactically incorrect, the conditional expression's return value is 2. If the shell option nocasematch is enabled, the match is performed without regard to the case of alphabetic characters. Substrings matched by parenthesized subexpressions within the regular expression are saved in the array variable BASH_REMATCH. The element of BASH_REMATCH with index 0 is the portion of the string matching the entire regular expression. The element of BASH_REMATCH with index n is the portion of the string matching the nth parenthesized subexpression.

score 0 · Answer 2 · edited Nov 11 '14 at 01:15

0

In ~ is saved your home directory (for example: /home/username) and = is assignment operator.

If you run this code in bash:

x=~       # variable x will hold string value /home/your_username
echo $x   # print variable x via echo command

it will print something like: /home/your_username

edited Nov 11 '14 at 01:15

Keith Thompson

254,901
44
429
631

answered Nov 11 '14 at 00:59

Tomáš Gašpar

29
3

2

True, but not at all likely to be what the OP is asking about. Bash does have an `=~` operator; see the other answer. – Keith Thompson Nov 11 '14 at 01:19

What does the =~ operator do?

2 Answers2