# netstat -r
Kernel IP routing table
Destination Gateway Genmask Flags MSS Window irtt Iface
192.168.30.0 * 255.255.255.0 U 0 0 0 eth0
169.254.0.0 * 255.255.0.0 U 0 0 0 eth0
default 192.168.30.1 0.0.0.0 UG 0 0 0 eth0
#
Code:
# ping 192.168.20.10
PING 192.168.20.10 (192.168.20.10) 56(84) bytes of data.
64 bytes from 192.168.20.10: icmp_seq=1 ttl=254 time=4.03 ms
64 bytes from 192.168.20.10: icmp_seq=1 ttl=254 time=4.03 ms (DUP!)
64 bytes from 192.168.20.10: icmp_seq=2 ttl=254 time=0.734 ms
64 bytes from 192.168.20.10: icmp_seq=2 ttl=254 time=0.735 ms (DUP!)
Would anyone be so kind to explain to me the function of dup() in UNIX? As far as I am concerned, it duplicates a file descriptor. Under what circumstances would we need to duplicate a file descriptor in a UNIX environment?
Thank you.
vinchen (3 Replies)
I have met this code:
switch(fork()) {
case 0:
close(1);
dup(p);
close(p);
close(p);
execvp(<whatever>);
perror("Exec failed");
}
Can anyone tell me what this piece of code does?
Thx alot.. (1 Reply)
I'm having difficulty understanding the purposes of using dup/dup2 when involving forks.
for example, if we call fork() once, that is, we are creating a child process. In what cases would we need to use dup or dup2 to duplicate the file descriptors for standard output and standard error? What... (1 Reply)
Hi, I use this function (now modified with elif) for check if a pc is up: check_pc() {
$PING $PC 1 2> /dev/null
if ; then
check_dir #Other function
echo "Begin backup operation for $PC"
echo "$SMBTAR -s $PC -u $USER -p $PASS -x $SHARE$EXCL -t - | gzip -c >... (3 Replies)
when i want to replace standard output with output file
int out;
out = open("out", O_WRONLY)p;
dup2(out,1);
What Shall I do in case of appending??? I am using here O_WRONLY TO WRITE.BUT IF i wanna append, whats the word? (5 Replies)
Hi,
I have a requirement where I have to identify duplicates from a file based on the first 6 chars (It is fixed width file of 12 chars length) and whenever a duplicate row is found, its original and duplicate row's last 2 chars should be updated to all 0's if they are not same. (I mean last 2... (3 Replies)
Hi Gurus,
I need to count the duplicate records in file
file
abc
abc
def
ghi
ghi
jkl
I want to get below result:
abc ,2
abc, 2
def ,1
ghi ,2
ghi, 2
jkl ,1
or
abc ,2
def ,1 (3 Replies)
help with bash script!
im am working on this script to make sure my server will stay online, so i made this script..
HOSTS="192.168.138.155"
COUNT=4
pingtest(){
for myhost in "$@"
do
ping -c "$COUNT" "$myhost" &&return 1
done
return 0
}
if pingtest $HOSTS
#100% failed... (4 Replies)
The problematic directory is the following:
/root/.cache/deja-dup
This directory grows until my "/" is full and then the restoring activity fails.
I already tried to create a symbolic link with origin another partition where I have more space. However during the restoring activity ... (4 Replies)
Discussion started by: puertas12
4 Replies
LEARN ABOUT FREEBSD
nos-tun
NOS-TUN(8) BSD System Manager's Manual NOS-TUN(8)NAME
nos-tun -- implement ``nos'' or ``ka9q'' style IP over IP tunnel
SYNOPSIS
nos-tun -t tunnel -s source -d destination -p protocol_number [source] target
DESCRIPTION
The nos-tun utility is used to establish an nos style tunnel, (also known as ka9q or IP-IP tunnel) using a tun(4) kernel interface.
Tunnel is the name of the tunnel device /dev/tun0 for example.
Source and destination are the addresses used on the tunnel device. If you configure the tunnel against a cisco router, use a netmask of
``255.255.255.252'' on the cisco. This is because the tunnel is a point-to-point interface in the FreeBSD end, a concept cisco does not
really implement.
Protocol number sets tunnel mode. Original KA9Q NOS uses 94 but many people use 4 on the worldwide backbone of ampr.org.
Target is the address of the remote tunnel device, this must match the source address set on the remote end.
EXAMPLES
This end, a FreeBSD box on address 192.168.59.34:
nos-tun -t /dev/tun0 -s 192.168.61.1 -d 192.168.61.2 192.168.56.45
Remote cisco on address 192.168.56.45:
interface tunnel 0
ip address 192.168.61.2 255.255.255.252
tunnel mode nos
tunnel destination 192.168.59.34
tunnel source 192.168.56.45
AUTHORS
Nickolay N. Dudorov <nnd@itfs.nsk.su> wrote the program, Poul-Henning Kamp <phk@FreeBSD.org> wrote the man-page. Isao SEKI
<iseki@gongon.com> added a new flag, IP protocol number.
BUGS
We do not allow for setting our source address for multihomed machines.
BSD April 11, 1998 BSD