Useful Linux commands

Here is a list of useful commands to be executed on a Linux server (debian). Feel free to contribute by feeding this page with your own tricks and tips.

Telnet like

It is often required to test if a host[:port] is reachable and access is granted from a server. Best way to execute a telnet like command on a Linux console is to work with special files used to communcate with peripherals. Thus, in order to test tcp port 8000 on server 10.100.100.100, simply try to write in file /dev/tcp/10.100.100.100/8000 and add a return value depending on success or failure

Test disk speed

dd command allows to copy all or parts of a disk by bytes block without impact from content structure of the disk.

Command structure

oflag: 'dsync' to use synchronized I/O for data

 root@v2-dvp-sandbox-ixp-ubu-91:/home/ixp_adm# dd if=/dev/zero of=/tmp/test2.img bs=512 count=1000 oflag=dsync
1000+0 records in
1000+0 records out
512000 bytes (512 kB, 500 KiB) copied, 1.22846 s, 417 kB/s