12-12-2008
Finding longest common substring among filenames
I will be performing a task on several directories, each containing a large number of files (2500+) that follow a regular naming convention:
YYYY_MM_DD_XX.foo_bar.A.B.some_different_stuff.EXT
What I would like to do is automatically discover the part of the filenames that are common to all 2500 files, so that a script could use that as a base name. In practice, this will end up being "YYYY_MM_DD_XX.foo_bar."
I figured out as far as I'll have to use ls to get all the filenames, but there's no command that I know of that will find the largest substring that exists among a large number of strings. I thought perhaps there would be some sed guru out there that would find this problem trivial. You sed experts always blow my mind.
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LEARN ABOUT REDHAT
strstr
STRSTR(3) Linux Programmer's Manual STRSTR(3)
NAME
strstr - locate a substring
SYNOPSIS
#include <string.h>
char *strstr(const char *haystack, const char *needle);
DESCRIPTION
The strstr() function finds the first occurrence of the substring needle in the string haystack. The terminating ` ' characters are not
compared.
RETURN VALUE
The strstr() function returns a pointer to the beginning of the substring, or NULL if the substring is not found.
BUGS
Early versions of Linux libc (like 4.5.26) would not allow an empty argument. Later versions (like 4.6.27) work correctly, and return
haystack when needle is empty.
CONFORMING TO
ISO 9899
SEE ALSO
index(3), memchr(3), rindex(3), strchr(3), strpbrk(3), strsep(3), strspn(3), strtok(3)
GNU
1993-04-12 STRSTR(3)