What is the meaning of the following line in a variable in bash?
VAR=${TEMP:3}
3 Answers
This is variable expansion and works like this (notice this is only bash and ksh specific and will not work in a POSIX shell):
$ x=1234567890
$ echo ${x:3}
4567890
$ echo ${x:7}
890
$ echo ${x:3:5}
45678
${var:pos}means that the variablevaris expanded, starting from offsetpos.${var:pos:len}means that the variablevaris expanded, starting from offsetposwith lengthlen.
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2@kos It's not worth mentioning, because everything works in
zsh=) I made a diet script inzshand lost 10kg in 1 week.– chaosOct 6, 2015 at 12:45 -
zshfor sure makes you dumber at typing paths when you're not using it :)– kosOct 6, 2015 at 12:57 -
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1Ha, I love how the only answer attempting to really answer the question got -2 because of "not enough jQuery"! :)– kosOct 6, 2015 at 13:05
in bash it cuts away the first 3 characters of a (string) variable:
$ VAR="hello world"
$ echo ${VAR:3}
lo world
have a look at 'substring extraction' here: http://www.tldp.org/LDP/abs/html/string-manipulation.html .
answered Oct 6, 2015 at 12:32
This operator cuts off the first 3 characters of variable TEMP and assigns the rest to variable VAR.
:has also other meanings, it's a bash builtin command, for example. I wanted to differ from that, because the question is obviously not about that. What the user means is the:operator inside a variable name. I'm sorry, I don't want to annoy somebody, but your rollback makes no sense and should be reversed, but I don't want an edit-war here. Furthermore it's bash and scripting specific so why remove those tags?TEMPandVARvariables and changed the question the way that other answers lost the meaning.VARvariable. But, however, you're free to change that one thing back. I wanted to make the question more general, less specific. It was never meant to sabotage other answers.