#!/bin/sh
set -xe
getSum() { sum=($(md5sum "$1")); [ -n "${sum[0]}" ] && echo ${sum[0]} || echo "error in $FUNCNAME"; }
compSum() { expr match "$(getSum "$1")" "$(getSum "$2")" >/dev/null && echo "rm -f $1"; }
find /some/dirA -type f|while read A; do B=$(basename "${A}"); B="/some/dirB/${B}"
 if [ -f "${B}" ]; then compSum "${A}" "${B}"; else echo "no ${B}"; fi; done; exit 0

#!/bin/sh
# Set debug and exit-on-error flag. Good for testing purposes.
# Also note there's an "echo rm" safeguard instead of a plain "rm".
set -xe
# Functions are nice for keeping a group of commands executed often together
function getSum() { 
 # fill array with the output of the command
 sum=($(md5sum "$1"))
 # if the first item of the array isn't empty then echo the contents
 if [ -n "${sum[0]}" ]; then
  echo ${sum[0]}
 else
  # else the first item of the array is empty and some error occurred.
  echo "error in $FUNCNAME"
 fi
 }

compSum() { 
 # "expr" match is just another way of saying
 # "if string_content_a matches string_content_b then doSomething"
 # If the exit status of the command is zero we echo rm (else we don't do zilch)
 expr match "$(getSum "$1")" "$(getSum "$2")" >/dev/null && echo "rm -f $1"
 }

# Find files (type f) in path "/some/dirA" (placeholder, obviously), then
# read output of find into variable "A", then
find /some/dirA -type f | while read A; do
 # see if we can find a similarly named file in placeholder directoryname /some/dirB/
 B=$(basename "${A}"); B="/some/dirB/${B}"
 if [ -f "${B}" ]; then
  # if we find it then compare sums, 
  compSum "${A}" "${B}"
 else
  # if we don't find a similarly named file echo that.
  echo "no ${B}"
 fi
# exit for "find"'s "while" loop
done
# Always return zero for normal script execution finish
exit 0

#!/bin/sh -
# Set exit-on-error flag. Good for testing purposes.
set -e
# Find files (type f) in path "/some/dirA" (placeholder, obviously), then
# read output of find into variable "A", then
find /some/dirA -type f | while read A; do
 # see if we can find a similarly named file in placeholder directoryname /some/dirB/
 B=$(basename "${A}"); B="/some/dirB/${B}"
 if [ -f "${B}" ]; then
  # if we find it then we compare size, 
  sizeOfA=$(stat -c %s "${A}")
  sizeOfB=$(stat -c %s "${B}")
  if [ "$sizeOfA" -eq "$sizeOfB" ]; then
   # size matches: echo to stdout
   echo "${A} ($sizeOfA) = ${B} ($sizeOfB)."
  else
   # size doesn't match: echo to stderr
   echo "OMG TEH FILEZ MATCH0RZ NOT ${A} ($sizeOfA) = ${B} ($sizeOfB)." > /dev/stderr
  fi
 else
  # if we don't find a similarly named file echo that.
  echo "no ${B}"
 fi
# exit for "find"'s "while" loop
done
# Always return zero for normal script execution finish
exit 0