Might I suggest using basename()?
--- last.c.orig 2009-10-27 23:59:39.000000000 +0000
+++ last.c 2013-02-09 01:43:04.709416732 +0000
@@ -36,6 +36,7 @@
#include <ctype.h>
#include <err.h>
#include <fcntl.h>
+#include <libgen.h>
#include <paths.h>
#include <signal.h>
#include <stdio.h>
@@ -407,7 +408,7 @@
asctime(gmtime(&total))+11);
}
ct = ctime(&buf[0].ut_time);
- printf("\nwtmp begins %10.10s %*.*s %4.4s\n", ct, timesize, timesize,
+ printf("\n%s begins %10.10s %*.*s %4.4s\n", basename(file),
ct, timesize, timesize,
ct + 11, ct + 20);
}