Source code in the unix programming language

#!/bin/sh

A=Bell
B=Ball

# Traditional test command implementations test for equality and inequality
# but do not have a lexical comparison facility
if [ $A = $B ] ; then
  echo 'The strings are equal'
fi
if [ $A != $B ] ; then
  echo 'The strings are not equal'
fi

# All variables in the shell are strings, so numeric content cause no lexical problems
# 0 , -0 , 0.0 and 00 are all lexically different if tested using the above methods.

# However this may not be the case if other tools, such as awk are the slave instead of test.


#!/bin/bash

isint() {
  printf "%d" $1 >/dev/null 2>&1
}

compare() {
  local a=$1
  local b=$2

  [[ $a = $b ]] && echo "'$a' and '$b' are lexically equal"
  [[ $a != $b ]] && echo "'$a' and '$b' are not lexically equal"

  [[ $a > $b ]] && echo "'$a' is lexically after '$b'"
  [[ $a < $b ]] && echo "'$a' is lexically before '$b'"

  shopt -s nocasematch # Turn on case insensitivity

  [[ $a = $b ]] && echo "'$a' and '$b' are equal with case insensitivity"

  shopt -u nocasematch # Turn off case insensitivity

  # If args are numeric, perform some numeric comparisions
  if isint $a && isint $b
  then
     [[ $a -eq $b ]] && echo "$a is numerically equal to $b"
     [[ $a -gt $b ]] && echo "$a is numerically greater than $b"
     [[ $a -lt $b ]] && echo "$a is numerically less than $b"
  fi

  echo
}


compare foo foo
compare foo bar
compare FOO foo
compare 24 123
compare 50 20