Bash script for running multiple versions of `pg_ctl`, using `asdf` to manage the postgres versions

pgctl

#!/usr/bin/env bash
PROG="${0##*/}"
DIR="${0%/*}"

current_pg_version() {
  asdf current postgres | cut -d' ' -f1
}

DEFAULT_PG_VERSION=`current_pg_version`

usage() {
  cat 1>&2 <<EOF
usage: $PROG [-h] [-n] [-v] [-V VERSION] [start | stop | status]
This is a multi-version proxy for running "pg_ctl" commands.
The default version is ${DEFAULT_PG_VERSION}.

Options:
  -h          show this help
  -n          show the commands but do not run them
  -v          talk more
  -V VERSION  Operate on this VERSION of postgres
EOF
  exit
}

talk()  { echo 1>&2 "$*" ; }
vtalk() { (( verbose )) && talk "$*" ; }
error() { talk "$*" ; exit 1 ; }

run() {
  if (( norun )) ; then
    talk "(norun) $*"
  else
    vtalk "--> $*"
    $@
  fi
}

while getopts 'hnvV:' opt ; do
  case "$opt" in
    h) usage ;;
    n) norun=1 ;;
    v) verbose=1 ;;
    V) PG_VERSION="$OPTARG" ;;
  esac
done
shift $(( OPTIND - 1))

# set the default version
PG_VERSION=${PG_VERSION:-$DEFAULT_PG_VERSION}

PG_DIR="$HOME/.asdf/installs/postgres/$PG_VERSION"
[[ -d "$PG_DIR" ]] || error "No such version installed: $PG_VERSION"

PG_BIN="$PG_DIR/bin"
PG_DATA="$PG_DIR/data"

PG_CTL="$PG_BIN/pg_ctl"
PG_LOGFILE="$HOME/log/postgres-$PG_VERSION.log"

if (( $# > 0 )) ; then
  action="$1"
else
  case $PROG in
    *start)  action=start ;;
    *stop)   action=stop ;;
    *status) action=status ;;
    *ctl)    usage ;;
    *) talk "Don't know what $PROG does" ; usage ;;
  esac
fi

if [[ ! -e "$PG_LOGFILE" ]] ; then
  logdir=`dirname $PG_LOGFILE`
  run "mkdir -p $logdir"
  run "touch $PG_LOGFILE"
  run "chmod 1777 $PG_LOGFILE"
fi

run "$PG_CTL -D $PG_DATA -l $PG_LOGFILE $action"