iterate_shell_array.sh

# Iterate over some array using POSIX Shell

# Initial data
ARR="a:b:c:d"

# Iteration. Do whatever is needed instead of 'echo "$VAL"'.
IT="${ARR}:"; while [ -n "$IT" ]; do VAL="${IT%%:*}"; echo "$VAL"; IT="${IT#*:}"; done

# IMPORTANT!!! Add semicolon to the end of an array (IT="${ARR}:") to make stop condition working.
#              Otherwise you will get infinite loop.