Shell Programming and Scripting

here the sub directories are same only variable is directory name.
mkdir -p  $DIR/sub1
mkdir -p  $DIR/sub2
mkdir -p  $DIR/sub3
mkdir -p  $DIR/sub4
mkdir -p  $DIR/sub5

mkdir -p  $DIR1/sub1
mkdir -p  $DIR1/sub2
mkdir -p  $DIR1/sub3
mkdir -p  $DIR1/sub4
mkdir -p  $DIR1/sub5


if [ -d "$DIR" ]; then
          echo "dir=$DIR exists"
             if [ -d "$DIR1" ]; then
              echo "dir1=$DIR1 exists"
           else
                //all the mkdir will come here
               echo "$DIR does not exist"
              fi
 
        else
           //all the mkdir will come here
          echo "$DIR2 does not exist"
         fi

for DIR in foo bar root; do
  for SUBDIR in sub1 sub2 sub3 sub4 sub5; do
    mkdir -p ${DIR}/${SBDIR} 2>/devnull
  done
done

#!/bin/bash
mkdir -p dir{1..5}

for DIR in foo bar root; do
  for SUBDIR in sub1 sub2 sub3 sub4 sub5; do
    mkdir -p ${DIR}/${SBDIR} 2>/devnull
  done
done

#! /bin/ksh

typeset -i iCnt=0

while [ -d ./dir$iCnt ] ; do
     (( iCnt += 1 ))
done
mkdir ./dir$iCnt

exit $?

cd /usr
/bin/ls -ltd 001_case* | head -1 | read latest

#----------------------------------------------------------------------#
# Isolate number.                                                      #
#----------------------------------------------------------------------#
num=${latest##001_case}

#----------------------------------------------------------------------#
# Increment.                                                           #
#----------------------------------------------------------------------#
(( num += 1 ))

#----------------------------------------------------------------------#
# Make next directory.                                                 #
#----------------------------------------------------------------------#
mkdir -p /user/001_case$num