Swaps positional parameters in Bash script.

posparams.sh

#!/bin/bash
 
echo "before: $#: $@"
pos=1
for arg in "$@"; do
  echo "$pos: $arg"
  pos=$((pos + 1))
done
 
args=
pos=0
for arg in "$@"; do
  rpos=$(($# - pos - 1))
  args[rpos]="$arg"
  pos=$((pos + 1))
done
 
echo "array: ${#args[@]}: ${args[@]}"
pos=1
for arg in "${args[@]}"; do
  echo "$pos: $arg"
  pos=$((pos + 1))
done
 
set -- "${args[@]}"
 
echo "after: $#: $@"
pos=1
for arg in "$@"; do
  echo "$pos: $arg"
  pos=$((pos + 1))
done