How to handle more than 10 parameters in shell

Question

I am using bash shell on linux and want to use more than 10 parameters in shell script

Note that having 10 parameters will make it quite confusing. Perhaps it would be better to use options (e.g. `-a 1` or `--foo=bar`) instead. See `man getopt`, `man getopts`, and `man bash` for some options for doing that. — Mikel, Feb 06 '11 at 10:34
See also: [Why do bash command line arguments after 9 require curly brackets?](https://stackoverflow.com/questions/18318716/why-do-bash-command-line-arguments-after-9-require-curly-brackets) — John Kugelman, Apr 03 '20 at 16:37

Dennis Williamson · Accepted Answer · 2022-06-26T15:55:43.653

231

Use curly braces to set them off:

echo "${10}"

Any positional parameter can be saved in a variable to document its use and make later statements more readable:

city_name=${10}

If fewer parameters are passed then the value at the later positions will be unset.

You can also iterate over the positional parameters like this:

for arg

or

for arg in "$@"

or

while (( $# > 0 ))    # or [ $# -gt 0 ]
do
    echo "$1"
    shift
done

edited Jun 26 '22 at 15:55

answered Feb 06 '11 at 10:27

Dennis Williamson

4

Note that ${10} will work in bash, but will limit your portability since many implementations of sh only allow single digit specifications. – William Pursell Feb 06 '11 at 14:11
1

@William: There are some shells that won't accept it, such as the original legacy Bourne shell, but in addition to the shells I listed in another comment (Bash, dash, ksh and zsh), it also works in csh, tcsh and Busybox ash. – Dennis Williamson Feb 06 '11 at 15:34
2

@WilliamPursell `${10}` is defined [by POSIX](http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_06_02) – Zombo Dec 09 '16 at 19:15
3

Worrying about `${10}` working is only necessary when using very old implementations which are not standard compliant. Probably only of historical interest...and yet I have yet to ever use it! I suppose because best practice dictates that 10 arguments is way too many unless they are repeated, in which case you'll iterate over them with `"$@"` rather than enumerating them. – William Pursell Dec 10 '16 at 16:54

score 38 · Answer 2 · edited Mar 29 '20 at 05:05

38

You can have up to 256 parameters from 0 to 255 with:

${255}

edited Mar 29 '20 at 05:05

szafran

answered Feb 06 '11 at 10:29

lukuluku

7

I think that limit is dependent on the shell. Bash, dash, ksh and zsh don't seem to have it. `sh -c 'echo ${333}' /usr/bin/*` – Dennis Williamson Feb 06 '11 at 10:33
5

My shell comfortably goes up to 2 million `set $(seq 2097152); echo ${2097152}` – Zombo Dec 09 '16 at 19:32
2

You can run `getconf ARG_MAX` to find out the max number of parameters your system can handle. – Lorand Jan 17 '23 at 02:45

2 Answers2