Question

I’m using the excellent UNIX ‘comm’ command line utility in an application which I developed on a BSD platform (OSX). When I deployed to my Linux production server I found out that sadly, Ubuntu Linux’s ‘comm’ utility does not take the -i flag to indicate that the lines should be compared case-insensitive. Apparently the POSIX standard does not require the -i option.

So… I’m in a bind. I really need the -i option that works so well on BSD. I’ve gone so far to try to compile the BSD comm.c source code on the Linux box but I got:

http://svn.freebsd.org/viewvc/base/user/luigi/ipfw3-head/usr.bin/comm/comm.c?view=markup&pathrev=200559

me@host:~$ gcc comm.c 
comm.c: In function ‘getline’:
comm.c:195: warning: assignment makes pointer from integer without a cast
comm.c: In function ‘wcsicoll’:
comm.c:264: warning: assignment makes pointer from integer without a cast
comm.c:270: warning: assignment makes pointer from integer without a cast
/tmp/ccrvPbfz.o: In function `getline':
comm.c:(.text+0x421): undefined reference to `reallocf'
/tmp/ccrvPbfz.o: In function `wcsicoll':
comm.c:(.text+0x691): undefined reference to `reallocf'
comm.c:(.text+0x6ef): undefined reference to `reallocf'
collect2: ld returned 1 exit status

Does anyone have any suggestions as to how to get a version of comm on Linux that supports ‘comm -i’?

Thanks!

Answer 1

You can add the following in comm.c:

void *reallocf(void *ptr, size_t size)
{
    void *ret = realloc(ptr, size);
    if (ret == NULL) {
        free(ptr);
    }
    return ret;
}

You should be able to compile it then. Make sure comm.c has #include <stdlib.h> in it (it probably does that already).

The reason your compilation fails is because BSD comm.c uses reallocf() which is not a standard C function. But it is easy to write.