Convert Jar with dependencies generated by `mvn package assembly:single` into shell script

jar2sh

#!/usr/bin/env bash

main() {
  set -euxo pipefail
  local USAGE JSONNAME SHNAME
  readonly USAGE="usage: $0 <jar-with-dependencies>"
  readonly JSONNAME="${1-}"
  readonly SHNAME="${JSONNAME%jar}sh"

  if ! command -v file &>/dev/null; then
    echo 'install: file'>&2
    return 1
  elif [ $# -ne 1 ]; then
    echo "$USAGE" >&2
    return 1
  elif ! { [ -n "$JSONNAME" ] && [ -f "$JSONNAME" ];}; then
    echo "not found: '$JSONNAME'" >&2
    echo "$USAGE" >&2
    return 1
  elif ! [[ "$(file "$JSONNAME")" =~ ^.*jar:[[:space:]]Zip[[:space:]]archive[[:space:]]data.*$ ]]; then
    echo "invalid file: '$JSONNAME'"
    echo "$USAGE" >&2
    return 1
  fi
  cat<<'A'>"$SHNAME";cat "$JSONNAME">>"$SHNAME";chmod +x "$SHNAME"
#!/bin/sh
if ! command -v sed java&>/dev/null; then echo install: sed java>&2;exit 1;fi
t="`mktemp`"
sed 1,5d "$0">"$t";java -jar "$t";rm "$t"
exit $?
A
}
main "${@}"
exit $?

# convert jar into sh
$ ./jar2sh target/testj-1.0.jar

# execute jar as sh locally
$ ./testj-1.0.jar.sh

# install globally
$ sudo install testj-1.0.jar.sh /usr/local/bin/testj

# execute jar as sh globally
$ testj