Karthik Subramanian wrote:
Hi Folks,
I was dusting my old copy of Kernighan & Pike, and I remembered working out most of the examples on an antiquated unix machine in engineering school. I decided to try out some just for kicks, and I discovered something:
In page 51 of K&P, there's an example that runs od on a directory, and the dump actually shows the filenames. I tried doing that (running 'od .' ) on my linux box, and got this instead:
od: .: Is a directory 0000000
So why doesn't od work on directories? Could somebody shed some light on this, please!
Thanks in Advance, Karthik.
hi there,
hope the trace below on "od" tells you why : Note dns is a directory , an argument to "od" command.
open("dns", O_RDONLY|O_LARGEFILE) = 3
fstat64(3, {st_mode=S_IFDIR|0775, st_size=4096, ...}) = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x40056000
read(3, 0x40056000, 4096) = -1 EISDIR (Is a directory)
write(2, "od: ", 4od: ) = 4
write(2, "dns", 3dns) = 3
open("/usr/share/locale/en_US.iso885915/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en_US/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en.iso885915/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
open("/usr/share/locale/en/LC_MESSAGES/libc.mo", O_RDONLY) = -1 ENOENT (No such file or directory)
write(2, ": Is a directory", 16: Is a directory) = 16
write(2, "\n", 1
) = 1
close(3) = 0
munmap(0x40056000, 4096) = 0
fstat64(1, {st_mode=S_IFCHR|0620, st_rdev=makedev(136, 0), ...}) = 0 /* Success */
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x40056000
write(1, "0000000\n", 80000000
) = 8
munmap(0x40056000, 4096) = 0
_exit(1) = ?
hope that helps .
cheers, Amith
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