Bash: the peril of $10 args

zen — Thu, 03 Sep 2009 03:51:11 +0000

Bash command arguments only goes up to $9. For the 10th arguments, ${10} should be used, instead of $10.

Example: tenthargs.sh

#!/bin/bash
echo "$1 $2 $3 $4 $5 $6 $7 $8 $9 ${10}"

When invoked:

$ ./tenthargs.sh one two three four five six seven eight nine ten
# properly prints out:
# one two three four five six seven eight nine ten

if $10 is used instead of ${10}, upon running the result will be like this instead:

# one two three four five six seven eight nine one0

That is, bash understood $10 as the first parameter ($1) followed by a literal 0 instead of the ‘tenth args’.

Of course, I have added this to my bash notes.

.zugiart » bash