Using while loop without process substitution, while allowing global variable value modification inside the loop

Question

I have a script that when I run from a file manager (Filza), it return an error saying

command substitution: syntax error near unexpected token `('.
line 56: `paste -d'\n' <(echo "$var1") <(echo "$var2"))'

But when I run it from a terminal (./myscript.sh), it ran with no error. Here's the code that gave the error:

#!/bin/bash

var1="A
B
C"
var2="1
2
3"
globalvar=0

while read v1 && read v2; do
    globalvar=$(echo $v1 $v2)
done<<<$(paste -d'\n' <(echo "$var1") <(echo "$var2"))

As commented below, it's probably some shell doesn't allow process substitution, thus why it failed. This command is running on iOS environment (jailbroken). Is there alternative way to implement this? Thanks in advance!

You don't specify how you run the script from shell. If you run e.g. bash script.sh, but your shebang points to /bin/sh, the invocation from the file browser will use a different shell. You should also provide a complete script that you can reproduce the issue with, not just a snippet that you suspect. — al.
– al., Commented Dec 7, 2019 at 13:12
How could we have an idea without knowing what kind of a shell Filza provides? — oguz ismail
– oguz ismail, Commented Dec 7, 2019 at 13:34
Unfortunately that's a closed-source project and I couldn't find out what shell it's using too. — Gregor Isack
– Gregor Isack, Commented Dec 7, 2019 at 13:40

dash-o · Accepted Answer · 2019-12-07 15:57:50Z

1

Try using 'here document' (<<) instead of 'here string' (<<<). It is supported by most shells.

while read v1 && read v2; do
    globalvar=$(echo $v1 $v2)
done <<__END__
$(paste -d'\n' <(echo "$var1") <(echo "$var2"))
__END__

The other option is create a shell wrapper that will force bash (from the question, looks like bash is installed and working). Rename original script to script-run, and modify the shell script to call the script-run

#! /bin/sh
exec /bin/bash ${0%/*}/script-run "$@"

Or other equivalent.

answered Dec 7, 2019 at 15:57

dash-o

14.6k1 gold badge14 silver badges43 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Using while loop without process substitution, while allowing global variable value modification inside the loop

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related