41

Can anyone explain the difference between declare and typeset with real-life examples?

Improve this question

2 Answers 2

Reset to default
42

In bash, typeset and declare are exactly the same. The only difference is that typeset is considered obsolete.

typeset: typeset [-aAfFgilrtux] [-p] name[=value] ...
    Set variable values and attributes.

    Obsolete.  See `help declare'.

The man page even lists them in the same breath:

declare [-aAfFgilrtux] [-p] [name[=value] ...]
typeset [-aAfFgilrtux] [-p] [name[=value] ...]
    Declare variables and/or give them attributes.

typeset is portable to some other shells, for example, ksh93. If you are aiming for cross-shell portability, use typeset (and make sure that the way you are calling it is portable). If you don't care about such portability, use declare.

Improve this answer
5
  • can you please provide some example of where and why this use in bash script Commented Feb 25, 2013 at 8:54
  • 1
    ...like I said, they are exactly the same. I don't understand how I can differentiate them if they are so. Commented Feb 25, 2013 at 10:04
  • 2
    Good one. Note that "obsolete" just appears in help typeset, not in man typeset. Commented Jul 22, 2014 at 8:05
  • 3
    @ChrisDown, you wouldn't happen to know why, exactly, typeset is considered obsolete? Commented Oct 5, 2016 at 2:40
  • 4
    In bash 4.4 and later, it is changed to synonym instead of obsolete. help typeset => A synonym for `declare'. See `help declare'. Commented Aug 20, 2021 at 11:14
6

I know a case where declare is useful to avoid the evil eval : variable indirection :

$ var=foo
$ x=var
$ declare "$x=another_value"
$ echo $var
another_value
Improve this answer
5
  • 2
    This is a nice comment but how does that answer the question which is about typeset and declare? Commented Feb 25, 2013 at 16:40
  • 1
    This is already well answered by Chris Down, my response is just a case where it's usefull Commented Feb 25, 2013 at 17:31
  • 1
    Perhaps I wasn't clear. Comments should be comments, and answers should be answers. This is a comment, not an answer. Commented Feb 25, 2013 at 20:32
  • 9
    My snippet wouldn't clear in a comment Commented Feb 25, 2013 at 21:52
  • but you still can assign variables with typeset... just replace declare with typeset and you still get the same result. Commented Nov 28, 2017 at 15:14

You must log in to answer this question.

Start asking to get answers

Find the answer to your question by asking.

Ask question

Explore related questions

See similar questions with these tags.