Shell Programming and Scripting

I am having a file which has data like this:-
1,2,3,4,5,


But I need to remove the last comma from this file. So the data should be like
1,2,3,4,5


The command I tried was


temp=`cat ${FileName}.txt`

len=`awk '{print length($0)}' ${FileName}.txt`

len=`expr $len - 1`

temp=`expr substr $temp 1 $len`



The problem here i am facing is if the data inside the file is very huge (say 1,2,3,4......9999,10000,)then it is giving error because the command (len=`awk '{print length($0)}' ${FileName}.txt`) returns two values for the variable like

len=10239

8651



Due to this the subsequent command fails.



Any help in this regard please.



Thanks & Regards,

Rony

Code:

 sed 's/,$//' filename > newfilename

Thanks Jim for your quick reply.

But for the sed command also i am getting it correct if the data is less but when it becomes big (say 1,2,3....5000,) it fails to write to the new file. So the new file is created as an empty file.

So is this is a limitation of UNIX or can we have some other work around for the problem.

Please help.

Thanks & Regards,
Rony

Yes. sed, vi, and other UNIX utilities that work on lines in files have a file record length limit. It's usually 2048 bytes per line (or record).

Look into fold to break lines into smaller pieces. Maybe. If you really have 1....5000
then you'll have to use C

Code:

/* cchop.c */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

/* if line ends in a comma, remove that ending comma */
/* usage  cchop < oldfile > newfile  - ONLY uses stdin stdout*/

int main(void)
{
	char tmp[64000]={0x0};  /*WAAAAY oversize */
	size_t len=0;
	
	while(fgets(tmp,sizeof(tmp),stdin)!=NULL)
	{
		char *p=strchr(tmp,0);
		p--;
		while(*p=='\n' || *p==',') 
		{
			*p=0x0;
			p--;
		}
		fprintf(stdout,"%s\n",tmp);
	}
	return 0;
}

Compile that and try it.

Thanks Jim. But i need to do it with shell script itself.

By the way if i change the structure of my source file as
1,
2,
3,
4,
5,
then the above problem of limitaion of length to a single record won't be there right? In that case how do i get the output as
1,2,3,4,5 ( no comma at the end).

I tried like this
awk 'sub(/$/,""){printf $0;next}
END { sub(/$/,""){printf $0;}
}' filename > newfilename

But this is giving me some error. How do i proceed with this??

Thanks,
Rony

The above command works if I put it like this

awk 'sub(/$/,""){printf $0;next}' filename>newfilename

But then the output would be
1,2,3,4,5,
The last comma (after 5) should not be there in the output.

Any help please

Try this :

Code:

awk '{line=line $0} END {sub(/,$/, "", line) ;print line}'