By default untaring will put the contents into the current directory.
Sometimes it is not desirable to change directory to the target (such as in a scrip).
tar -xvvf /source/tarfile.tar -C /target |
This will extract(x), very verbosly(vv) the file(f) /source/tarfile.tar to the directory(-C) /target (it will change the output folder to /target (so make sure it exists).
netstat can be used to figure out what program is using a port.
$ netstat -nlp Active Internet connections (only servers) Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 1096/sshd tcp 0 0 0.0.0.0:80 0.0.0.0:* LISTEN 1733/apache2 tcp6 0 0 :::22 :::* LISTEN 1096/sshd Active UNIX domain sockets (only servers) Proto RefCnt Flags Type State I-Node PID/Program name Path unix 2 [ ACC ] STREAM LISTENING 6338 1071/gdm-simple-sla @/tmp/gdm-greeter-LvjLQPzT unix 2 [ ACC ] STREAM LISTENING 5165 1072/X /tmp/.X11-unix/X0 |
If you have a lot open then grep can be used to only find what you are looking for
netstat -nlp|grep :22 tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 1096/sshd tcp6 0 0 :::22 :::* LISTEN 1096/sshd |
For windows, simply start with
netstat -n |
The arp cache should (normally) be cleared within 20 minutes (or less, this depends on what platform is used).
If you don’t know what ARP is and what is is good for, then perhaps you should take a moment and read the man page:
DESCRIPTION Arp manipulates or displays the kernels IPv4 network neighbor cache. It can add entries to the table, delete one or display the current content. ARP stands for Address Resolution Protocol, which is used to find the media access control address of a network neighbor for a given IPv4 Address. |
On a windows platform to show the arp cache
C:\> arp -a Interface: 192.168.1.49 --- 0xb Internet Address Physical Address Type 192.168.1.29 00-1d-92-08-49-25 dynamic 192.168.1.34 00-24-81-85-ab-b6 dynamic |
To clear the cache
C:\>netsh interface ip delete arpcache Ok. |
To show the arp cache on a nix machine:
$ arp -vn; cat /proc/net/arp Address HWtype HWaddress Flags Mask Iface 192.168.1.254 ether 00:08:ae:09:20:a0 C eth0 IP address HW type Flags HW address Mask Device 192.168.1.254 0x1 0x2 00:08:ae:09:20:a0 * eth0 |
To clear the apr cache on a nix machine.
$ ip neigh flush all |
sendmail expects to the machine to have a FQDN (fully qualified domain name).
If it does not have that (type “hostname” to check what name the machine has) sendmail will complain about this and take a loot of extra time trying to find it.
To use a FQDN edit “/etc/hosts” and change [something] to [something.yourdomain.com] and this will go away. Updating “/etc/hostname” at the same time might be a good idea; don’t forget to run “/bin/hostname -F /etc/hostname” after updating /etc/hostname.