logcmd
#define LOGCMD(cmd, file) logcmd((cmd), (file), NULL, -1)
#define LOGCMD2(cmd, file1, file2) logcmd((cmd), (file1), (file2), -1)
#define LOGBYTES(cmd, file, cnt) logcmd((cmd), (file), NULL, (cnt))
static void logcmd(char *, char *, char *, off_t);