a cheap substitute for util-linux rename

rename.c

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


int main(int argc, char **argv)
{
    int n, diff, fromlen, tolen, leftlen;
    const char *name, *from, *to, *pos;
    char *buf;

    if (argc < 4) {
        fprintf(stderr, "usage: %s from to files...\n", argv[0]);
        return 1;
    }

    from = argv[1];
    to = argv[2];
    fromlen = strlen(from);
    tolen = strlen(to);
    diff = tolen - fromlen;

    for (n = 3; n < argc; n++) {
        name = argv[n];
        pos = strstr(name, from);
        if (!pos) continue;
        leftlen = pos - name;
        buf = malloc(strlen(name) + diff + 1);
        memcpy(buf, name, leftlen);
        memcpy(buf + leftlen, to, tolen);
        memcpy(buf + leftlen + tolen, pos + fromlen, strlen(name) + diff - leftlen - tolen + 1);
        rename(name, buf);
        free(buf);
    }

    return 0;
}