How to solve compability problem the code printf in bash and sh?

Question

I write a basic script which it has colourful lines in it.

#!/bin/bash

g="\e[32m"
_0="\e[0m"

printf "$g name $_0"

The script runs normally but at shellcheck.net I got this message: Don't use variables in the printf format string.

Another problem when I convert my script to #!/bin/sh my script doesn't run correctly, giving this output:

\e[32m name \e[0m

I used echo -e but this time sh said that -e wasn't supported. How do I write a common line of code to solve this problem? Thank you.

This is almost https://unix.stackexchange.com/q/205497/5132 again. — JdeBP, Dec 17 '19 at 14:08
Thanks. Yes it works with bash but not with sh Is there a way that work with both? — , Dec 17 '19 at 14:30

score 2 · Answer 1 · answered Dec 17 '19 at 14:29

2

You can use this, will work either on bash or sh:

#!/bin/bash

# \e not supported by POSIX; use \033 (octal) instead.
g=$(printf '\033[32m')
_0=$(printf '\033[0m')

printf '%s name %s foo' "$g" "$_0"

answered Dec 17 '19 at 14:29

Thanks that's the anwser I was looking for! Plus, why shellcheck.net saysDon't use variables in the printf format string. Is there a solid reason? – Dec 17 '19 at 14:40
1

@AhmetMehmet It makes it very difficult to print strings contains backslashes and percentage signs for starters. – Kusalananda Dec 17 '19 at 14:55
1

To print to a variable in bash, use e.g. printf -v _0 '\033[0m'. No need for the command substitution. – Kusalananda Dec 17 '19 at 14:56
Thanks I see. Is there a site to show all characters octal forms like \033 I find different things? – Dec 17 '19 at 15:57
1

You can check here – schrodingerscatcuriosity Dec 17 '19 at 16:15
1

Or use man ascii. And https://unix.stackexchange.com/q/371827/5132 gives one reason that this answer is as it is. – JdeBP Dec 18 '19 at 12:32

1 Answers1