Random Hints and Tips

From CafeWiki

An assortment of command and tips to do various interesting (and sometimes important) things on a linux box:

What CPU have I got?

$cat /proc/cpuinfo

How much memory?

$cat /proc/meminfo

More detailed CPU/system information?

$sudo lshw

What version of linux is this anyway (2 methods)?

$lsb_release –a
$cat /etc/issue

Who are the users on the system?

$cat /etc/passwd

What groups are on the system?

$cat /etc/group

How is a user added? This can be tricky as there is an "adduser" command that works differently, in some cases, it might be even easier to just use the webmin interface if you have it installed.

$useradd username 

How do I reboot the box from the CLI (2 methods)?

$sudo reboot 
$sudo shutdown -r 0

How to I (securely) copy a file from one server to another server? This works to send a file to another server as well, see this example. Switches are -p to preserve permissions and modification times, -r for recursive copying of a directory.

$scp [-p][-r] [[user@]from-host:]source-file [[user@]to-host:][destination-file]

How do I find previous commands in the history file? See this site for more examples.

$<ctrl-r>
(reverse-i-search)`red': [search-string]  {left or right arrow allows edits}

$history | grep [search-string]

How do I execute a specific command from the history? (Once the command number is known, e.g. from grepping the history)

$![cmd-number]

How do I capture a command line session, both commands and responses (Ref)?

$script filename
$<enter commands as desired>
...
$ctrl-d <to exit>