John W. Krahn wrote:
> Saravana Kumar wrote:
>> Hi,
>
> Hello,
>
>> I am new to the list and newbie in perl.
>>
>> I have a big flat file(100G). The file was supposed to be in a single
>> line but many of records(as it has ^M). There are also ^@ and tabs in
>> between.
>>
>> I want to first replace the control characters and tabs with space.
>>
>> I tried this s/[[:cntrl:]\t]/ /g.
>
> The [:cntrl:] character class includes the "\t" character.
>
>
>> After replacing the above said characters
>> with space i have to insert \n after each 1000th character.
>>
>> But the program hangs after reading about 24G( 1/4th of the file).
>>
>> I thought of reading the file character by character, check if the
>> character is ^M||^@||\t. If true replace with the space and write the
>> ouput else
>> simply write the output. I have to keep track of the count of characters
>> so as to insert \n after each 1000th character.
>>
>> Will the above work or is there any other(simple) way to do this?( or
>> should i just move on to C?)
>>
>> I am not sure why my first program hang(i ran the program in a machine
>> with 2G RAM).
>
> You can do what you want if you set the Input Record Separator to read
> 1000 bytes at a time:
>
> $/ = \1000;
> while ( <FILE> ) {
> s/[[:cntrl:]]/ /g;
> print "$_\n";
> }
>
>
>
> John
Thanks John. That did the trick. I ran the above script with my input file
and redirected the output to another file. Since it is creating a new file
i was wondering whether i can do the changes in the same file ie., read
1000 characters, do the replacement and write the output to the same file.
This will reduce the disk space used(since the file i have is 100G).
TIA,
SK
--
To unsubscribe, e-mail: [EMAIL PROTECTED]
For additional commands, e-mail: [EMAIL PROTECTED]
<http://learn.perl.org/> <http://learn.perl.org/first-response>
