docker-sh: start a shell session with the container passed

docker-sh

#!/usr/bin/env bash

if [ "$#" -ne 1 -o "$1" == "-h" -o "$1" == "--help" ]; then
  echo 'docker-sh: start a shell session with the container passed'
  echo
  echo "Use: docker-sh CONTAINER_NAME"
  echo
  echo "NOTE: partial names can be used, but the session"
  echo "      is started only if one container match"
  exit 2
fi

CONTAINER=$(docker ps -f name=$1 -q)

NL=$'\n'
if [[ $CONTAINER == *$NL* ]]; then
  echo "More than one container match the name \"$1\":"
  echo
  docker ps -f name=$1 --format "{{.Names}}"
  echo
  echo "Check available containers with 'docker ps -f name=NAME'."
  exit 3
fi

if [ "$CONTAINER" == "" ]; then
  echo "No container match the name \"$1\", or your container exited."
  echo "Check available and exited containers with 'docker ps -a -f name=NAME'."
  exit 4
fi

docker exec -it $CONTAINER sh