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bashshellstring-concatenation

Concatenating variables in Bash

I am trying to add a variable to the middle of a variable, so for instance in PHP I would do this:

$mystring = $arg1 . '12' . $arg2 . 'endoffile';

so the output might be 20121201endoffile, how can I achieve the same in a linux bash script?

Solution

  • Try doing this, there's no special character to concatenate in bash :

    mystring="${arg1}12${arg2}endoffile"

    explanations

    If you don't put brackets, you will ask to concatenate $arg112 + $argendoffile (I guess that's not what you asked) like in the following example :

    mystring="$arg112$arg2endoffile"

    The brackets are delimiters for the variables when needed. When not needed, you can use it or not.

    another solution

    (less portable : require bash > 3.1)

    $ arg1=foo
$ arg2=bar
$ mystring="$arg1"
$ mystring+="12"
$ mystring+="$arg2"
$ mystring+="endoffile"
$ echo "$mystring"
foo12barendoffile

    See http://mywiki.wooledge.org/BashFAQ/013