#!/bin/ksh
 
 /bin/rm index.dat
 
 set -A USER_HOME  /tmp/UserA /tmp/UserB /tmp/UserC /tmp/Root /tmp/GroupA /tmp/GroupB
 set -A USERS UserA UserB UserC Root GroupA GroupB
 
 for v in   ${USERS[*]} ; do
   find /tmp/$v -type f | awk -F. ' (NF == 2 ){ print $2 }' | sort -ud | tee -a index.dat
 done
 
 for type in $(<index.dat); do
   NewDir=/tmp/${type}-IndexedFileDir
   mkdir -p $NewDir
   find ${USER_HOME[*]} -type f -name "*.$type" -print | xargs -I{} -t mv {} ${NewDir}
 done

#!/bin/sh
awk -v user="user1" ' BEGIN {  path = " /home/" user "/";command = "ls" path ;
              while ( (command | getline line)>0 ) {                          
                            if (line ~ /\....$/) {
                                          ext = substr(line,length(line)-2)
                                          Extension[ext]    
                                          files[line] = ext
                            }                            
              }
            }
        END {   makedircmd = "mkdir "
                for ( e in Extension) {
                     print "making " path e                     
                     dir = path e
                     makedircmd = makedircmd dir                                      
                     print makedircmd
                 }
                 #system(makedircmd) #uncomment to use
                 for (f in files) {
                            mvcmd = "mv" path f " " path files[f]
                            traceback = "mv" path files[f] "/" f path 
                            print traceback
                            print traceback >> "backup.sh" #backup
                            #system(mvcmd) #uncomment to use
                 }
        }

' "file"

user="TEST" ' BEGIN {  path = " /home/rosman/" user "/";command = "ls" path

[rosman]: /home/rosman/TEST => backup.sh
awk: 0602-533 Cannot find or open file file.
 The source line number is 1.

..
print traceback > "backup.sh" ( single > )
...