... replace the first entry in file1.txt(JO EMS Math) with my row in file2.txt (Jon EMS Physics) without changing the row format like padding and spacing.

I don't understand what "padding" means in the context of your question. (In general, I don't understand the context of your question.) I don't understand how "spacing" can be expected to remain the same when two of the three replacement fields have different widths.

I stored and worked on @ ...

I don't understand what @ is.

... and was able to do the replacement however the padding and spacing changed.

Can you please show a Short, Self-Contained, Correct Example of what you have done so far? It might do much to clear up my misunderstandings.

Also: Is this a school assignment? It sure looks like one. If it is, please tell us and we will be better able to offer appropriate help.

G'day sabas,

As already stated, your question is somewhat vague and doesn't give us a lot to work on. We're happy to help you out with things you're stuck on (e.g. some aspect of Perl you're having difficulty understanding) but this is not a code writing service. Another good resource to help you improve your posts is "How do I post a question effectively?".

"... without changing the row format like padding and spacing."

Have a look at the printf and sprintf functions. These may help with this aspect of your problem. Here's a quick example:

$ perl -e '
    my $fmt = "%7s %7s %7s\n";
    my $x = "JO EMS Math";
    my $y = "Jon EMS Physics";
    printf $fmt, split " ", $_ for $x, $y;
'
     JO     EMS    Math
    Jon     EMS Physics
[download]

I apologize for my elementary coding in Perl. I am a beginner and I been debugging this for a over 3 days and i cannot figure out....the idea i am making is this: file1.txt aaa bbb ccc file2.txt ddd eee fff ggg hhh ggg file3.txt should looks like these: aaa bbb ccc ggg hhh ggg the length of my rows are over 381 and when i wrote it to file3.txt the length becomes < 200 and the padding (space) for each column became one space only per column.

# CREATING UPDATE FILE FEATURE
    my $tmp = "$workingDir/CR/EGIS_table.txt";
    open(my $fh, '<:encoding(UTF-8)', $tmp) or die "Could not open fil
+e '$tmp' $!";
    my @rows = <$fh>;
    chomp @rows;

    if ($updatefile) {  # logical and operator if the update=1 and the
+ filename exist then go down

        my $tmp = "$workingDir/CR/EGIS_table.txt";
        open(my $fh, '<:encoding(UTF-8)', $tmp) or die "Could not open
+ file '$tmp' $!";
        my @rows = <$fh>;
        chomp @rows;
        #FORMAT AND PAD THE FIELDS WITH SPACES IN LEFT JUSTIFIED BEFOR
+E WRITING TO FILE
        $file_requesterName = sprintf('%-30s',$file_requesterName);
        $file_requesterEmail = sprintf('%-35s',$file_requesterEmail);
        $file_reqtype = sprintf('%-15s', $file_reqtype);
        $file_region = sprintf('%-15s',$file_region);
        $file_Serial_Number = sprintf('%-15s', $file_Serial_Number);
        $file_aiws_OSS_IP_pri = sprintf('%-15s', $file_aiws_OSS_IP_pri
+);
        $file_aiws_OSS_IP_sec = sprintf('%-15s', $file_aiws_OSS_IP_sec
+);
        $file_temp_SGW_IP_pri = sprintf('%-15s', $file_temp_SGW_IP_pri
+);
        $file_temp_SGW_IP_sec = sprintf('%-15s', $file_temp_SGW_IP_sec
+);
        $file_bts_site_id = sprintf('%-15s', $file_bts_site_id);
        $file_req_date = sprintf('%-15s', $file_req_date);
        $file_NOC_Update_req = sprintf('%-19s', $file_NOC_Update_req);
        $file_OSS_enm = sprintf('%-11s', $file_OSS_enm);
        $file_category = sprintf('%-15s', $file_category);
        $file_RNC_Name = sprintf('%-10s', $file_RNC_Name);
        $file_submission_status = sprintf('%-15s',$file_submission_sta
+tus);
        $file_additionalnotes = sprintf('%-100s',$file_additionalnotes
+);

        # WRITING TEMPORARY UPDATED ROW INTO TEMPORARY FILE TO BE USED
+ LATER IN UPDATING THE EGIS_table.txt (MASTER TABLE)        

        my $temporary_fileName = "$workingDir/CR/EGIS_table_oneline.tx
+t";
        open ($fh, '>', $temporary_fileName) or die $!;
        `echo "$file_requesterName $file_requesterEmail $file_reqtype 
+$file_region $file_Serial_Number $file_aiws_OSS_IP_pri $file_aiws_OSS
+_IP_sec $file_temp_SGW_IP_pri $file_temp_SGW_IP_sec $file_bts_site_id
+ $file_req_date $file_NOC_Update_req $file_OSS_enm $file_category $fi
+le_RNC_Name $file_submission_status $file_additionalnotes \n" > $temp
+orary_fileName`;
        close ($fh);

        # END OF WRITING TEMPORARY UPDATED ROW INTO TEMPORARY FILE TO 
+BE USED LATER IN UPDATING THE EGIS_table.txt (MASTER TABLE)        
        
        my $index=1;

        # UPDATE THE ARRAY INDEX THAT WAS EDITED BY THE USER
        foreach my $row(@rows) {        
            next if $row =~ /REQUESTER_NAME/;  # SKIP THE HEADER OF TH
+E TABLE
            if ($index == $submit_button) {   # IF ARRAY INDEX = SUBMI
+T_BUTTON THEN UPDATE THE CONTENT OF AN ARRAY. Example index=13 and yo
+u change the requester name to Alvin and hit the submit button, only 
+index 13 will be updated.
                print "The Submit Button was Pressed and the array ind
+ex=" . $submit_button;
                @rows[$submit_button] = $file_requesterName . $file_re
+questerEmail . $file_reqtype . $file_region . $file_Serial_Number . $
+file_aiws_OSS_IP_pri . $file_aiws_OSS_IP_sec . $file_temp_SGW_IP_pri 
+. $file_temp_SGW_IP_sec . $file_bts_site_id . $file_req_date . $file_
+NOC_Update_req . $file_OSS_enm . $file_category . $file_RNC_Name  . $
+file_submission_status . $file_additionalnotes;      
                print "ROWS=@rows[$submit_button]";
            }
            $index++;
        }        

        $index--;

        # print "Array Index Total Row=" . $index;

        # STORE TEMPORARILY THE UPDATED DATA HERE
        my $EGIS_table_fileName_tmp = "$workingDir/CR/EGIS_table_tmp.t
+xt";
        open(EGIS_table_fileName_tmp_fh, '>:encoding(UTF-8)', $EGIS_ta
+ble_fileName_tmp) or die "Could not open file '$EGIS_table_fileName_t
+mp' $!";
        
        
        # ORIGINAL FORMATTED FILE WITH PADDED with space COLUMNS
        my $EGIS_table_fileName = "$workingDir/CR/EGIS_table.txt";    
+    
        open(EGIS_table_fileName_fh, '<:encoding(UTF-8)', $EGIS_table_
+fileName) or die "Could not open file '$EGIS_table_fileName' $!";

        # FILE THAT HOLDS THE USER CHANGED ROW
        my $EGIS_table_fileName_oneline = "$workingDir/CR/EGIS_table_o
+neline.txt";        
        open(EGIS_table_fileName_oneline_fh, '<:encoding(UTF-8)', $EGI
+S_table_fileName_oneline) or die "Could not open file '$EGIS_table_fi
+leName_oneline' $!";

        # STORE THE CONTENT OF EGIS_TABLE_ONELINE.TXT into variable
        my $oneline_content;
        open(my $fh, '<', $EGIS_table_fileName_oneline) or die "cannot
+ open file $EGIS_table_fileName_oneline";
        {
            local $/;
            $oneline_content = <$fh>;
        }
        close($fh);

        print "One line txt file content=$oneline_content";

         my $j=0;
         print "*SUBMIT_BUTTON=$submit_button*";

        while (my $row = <EGIS_table_fileName_fh>) {
          chomp $row;
          print "Hello";
          my $row_length = length($row);
          print "THE LENGTH OF ROW=$row_length";
          $j++;
          if ($j==$submit_button) {  # IF THE ROW IS THE DATA TO BE CH
+ANGED then OPEN THE FILE AND REPLACE THE ROW WITH UPDATED ONE
              print "***** Matching Row Found ******";
              print "From File Row=$row*";
              $row = "$file_requesterName $file_requesterEmail $file_r
+eqtype $file_region $file_Serial_Number $file_aiws_OSS_IP_pri $file_a
+iws_OSS_IP_sec $file_temp_SGW_IP_pri $file_temp_SGW_IP_sec $file_bts_
+site_id $file_req_date $file_NOC_Update_req $file_OSS_enm $file_categ
+ory $file_RNC_Name $file_submission_status $file_additionalnotes";
            print "New Row=$row*";
            `echo $row >> $EGIS_table_fileName_tmp`;     # THIS IS NOT
+ WORKINGGGGGGGGGGGGGGGGGGGGGGGGG!
          } else {  # IF THE ROW IS NOT TO BE CHANGED JUST WRITE IT DO
+WN AS IS
              print "***** NotMatching Row Found Writing straight to E
+GIS_table_tmp.txt******";
            print $row;
            `echo $row >> $EGIS_table_fileName_tmp`;      # THIS IS NO
+T WORKINGGGGGGGGGGGGGGGGGGGGGGGGG!
          }

        }

        close (EGIS_table_fileName_tmp_fh);
        close (EGIS_table_fileName_fh);

        copy $EGIS_table_fileName_tmp, $EGIS_table_fileName;

    }  # END OF CREATING UPDATE FILE FEATURE
[download]

and the padding (space) for each column became one space only per column.

`echo $row >> $EGIS_table_fileName_tmp`;     # THIS IS NOT WORKINGGGGGGGGGGGGGGGGGGGGGGGGG!

The problem is that instead of opening a file and printing to it you are instead shelling out and running echo from the shell which by default collapses multiple spaces into just one.

Have a good read through perlintro, especially the part about how to write to files from within Perl in the section Files and I/O. Good luck.

Seconding hippo's comment, perhaps it helps to understand that

print "something";
[download]

(which you are already using), is just an abbreviation for

print STDOUT "something";
[download]

and instead of

        open ($fh, '>', $temporary_fileName) or die $!;
        `echo "... long string ..." > $temporary_fileName`;
        close ($fh);
[download]

where open and close are effectively useless, you should use

        open ($fh, '>', $temporary_fileName) or die $!;
        print$fh "... long string ...";
        close ($fh);
[download]

(I prefer to put the file handle after print without a space to help remembering there's no comma after the file handle)

If you feel adventurous, you might to look over Text::Table Tutorial, but that's an advanced topic, just to see what's possible.

sabas--

Your code is frightening. You need to learn how to read code and understand what's happening inside it. Your code has three different places where you're creating the desired row of data (one which looks just fine) and then you're playing with temporary files in desperate attempts at trying to somehow get the data into the file you want.

It looks like it would work if you'd remove all the junk you don't really need. I was able to cut your code down into something that looks reasonable in less than 40 lines. I'd ordinarily make a long post describing some ways to improve your code, but I don't have the time to do it today. Instead I'll show you the line that looks like it would work (I changed @rows to $rows to eliminate a warning):

$rows[$submit_button] = $file_requesterName . $file_requesterEmail . $
+file_reqtype . $file_region . $file_Serial_Number . $file_aiws_OSS_IP
+_pri . $file_aiws_OSS_IP_sec . $file_temp_SGW_IP_pri . $file_temp_SGW
+_IP_sec . $file_bts_site_id . $file_req_date . $file_NOC_Update_req .
+ $file_OSS_enm . $file_category . $file_RNC_Name  . $file_submission_
+status . $file_additionalnotes;
[download]

Since that line puts the data in the correct format into @rows, you can delete the code dealing with temporary files and just write the @rows data to the output file.

...roboticus

When your only tool is a hammer, all problems look like your thumb.