Differences between declare, typeset and local variable in Bash

bash shell variables scope declare
lecodesportif picture lecodesportif · Dec 12, 2010 · Viewed 22.4k times · Source

When typing variables in Bash, what is the difference between declare and typeset? When used inside a function: what is the difference between declare and typeset and local?

The only difference I have come across is that typeset is portable to ksh scripts. Other than that, are there any reasons why one should be preferred over the other?

UPDATE: Added local to the question.

Answer

Hui Zheng picture Hui Zheng · Apr 18, 2012
  • Difference between typeset and declare:

The former is more portable(e.g. ksh), while the latter is more preferable when portability is not a concern.

  • Difference between declare(or typeset) and local when used inside a function:

The former implies the latter, but more powerful. For example, declare -i x makes x have the integer attribute, declare -r x makes x readonly, etc.

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