Syntax error when exectuting bash shell script from busybox

Question

Syntax error when executing a bash shell script from busybox

Script

#!/bin/bash
for dev in `cat /proc/partitions | awk '{print $4}'`; do
if cmp -s <(head -c 2 /dev/$dev) <(echo -n -e '\x38\x6e')
then
echo "OK"
break
fi
done

Error line 3

Syntax error: "(" unexpected

Answer 1

Busybox doesn't do bash, it only has a minimal sh-like shell. The <() syntax is specific to bash (and some other similar shells). It won't work with POSIX sh or busybox sh or any other minimal shell. That's why you're getting that error.

To get your script to work with busyboxh sh, try:

match=$'\x38\x63'
for dev in $(awk '/[0-9]/{print $NF}' /proc/partitions); do
        first=$(head -c 2 /dev/$dev)
        if [ "$first" = "$match" ]
        then
                echo "OK"
                break
        fi
done