Untitled

Converting Bash command line options to variable name
if [ ! -n $1 ]; then
   echo "Error"
fi

if test -s "${foo+set}"

if [ -z "$1" ]; then
   echo "Error"
   exit 1
fi

#!/bin/bash
USAGE="$0: [-a] [--alpha] [-b type] [--beta file] [-g|--gamma] args..."

ARGS=`POSIXLY_CORRECT=1 getopt -n "$0" -s bash -o ab:g -l alpha,beta:,gamma -- "$@"`
if [ $? -ne 0 ]
 then
  echo "$USAGE" >&2
  exit 1
 fi
eval set -- "$ARGS"
unset ARGS

while true
 do
  case "$1" in
   -a) echo "Option a"; shift;;
   --alpha) echo "Option alpha"; shift;;
   -b) echo "Option b, arg '$2'"; shift 2;;
   --beta) echo "Option beta, arg '$2'"; shift 2;;
   -g|--gamma) echo "Option g or gamma"; shift;;
   --) shift ; break ;;
    *) echo "Internal error!" ; exit 1 ;;
  esac
 done

echo Remaining args
for arg in "$@"
 do
  echo '--> '"`$arg'"
 done

exit 0

if [[ -z $1 ]]; then
    echo "Error"
fi

if [ ! -n "$1" ]; then
    echo "Error"
fi

-z string
      True if the length of string is zero.
 -n string
      True if the length of string is non-zero.

-v varname
      True if the shell variable varname is set (has been assigned a value).