bash Cookbook

Using for Loops Portably

Problem

You need to do a for loop but want it to work on older versions of bash.

Solution

This method is portable back to bash-2.04+:

$ for ((i=0; i<10; i++)); do echo $i; done
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Discussion

There are nicer ways of writing this loop in newer versions of bash, but they are not backwards compatible. As of bash-3.0+ you can use the syntax for {x..y}, as in:

$ for i in {1..10}; do echo $i; done
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If your system has the seq command, you could also do this:

$ for i in $(seq 1 10); do echo $i; done
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See Also

• help for

• man seq

• Looping with a Count

• Looping with Floating-Point Values

• Writing Sequences