Interesting Unix Commands

[ZeroCold]

Interesting UNIX Commands

Ever since renting a UNIX handbook a while back ive discovered lots of the more

complex operations and commands of UNIX, besides the mundane, and ordinary

asks of running an maintaining an eggdrop. I therefore went through my UNIX

Handbook picking out some of the less mentioned, useful comands, and here

they are:

mailx - This program will send an email to someone just like that. The syntax

is 'mailx user@host' you then enter your message.

mesg - This command is used to disable or enable the ability of users being

able to 'write' to you.

uname - This basically returns the version of UNIX the box is running. There

are various switches for this command.

wall - Sends a public message to ever user on the box, as if you had 'writen'

to each and ever user. Good for admins.

banner - This reutrns an ASCII banner for a word or letter you specify. So

'banner shell' would outpub shell in big ASCII

uncompress - This decompresses .Z files. For example 'uncompress shell.Z'

would output a file 'shell'

tail - This shows the last 10 lines of a file. The -f option can also be

used to 'follow' a file as additions are made.

more - allows you to scroll a file. This is most often used when reading

MOTDs, by 'more /etc/motd'

ln - This is used to create links. For instance I could make shell-tests.txt

link to a file called tests by 'ln -s shell-tests.txt tests'

grep - This command is the equivilent of find. I use it a lot, when doing

tasks and adding the pipe symbol. Like 'ps aux | grep -c eggdrop' This

basically takes ps aux, and searches it for the amount of times eggdrop is

mentioned (hence -c for count)

crypt - This is used to encrypt text with a password. Simple encryption, but

easy to use, if you need to encrypt somthin.

chown - This changes ownership of files or directories to a group or user.

Very useful for administration tasks.

cat - This is the equivilent of type in DOS. All it does is prints out

(on your screen) the contents of a file.

su - This is usually associated with Super User'ing to root, however it

can also be used to login with a different login name. Use su <username>.

It will then prompt you for the pass of that user.

sleep - This command is like pause, however you need to specify a time in

seconds. This is usually used in scripts.

ruptime - This neat command lists all the boxes on the LAN, their uptime,

status, load averages and amount of users.

nohup - This command is a simple equivilent of screen. It basically keeps a

process alive even when you're logged out.

man - This stands for manual, and covers most topics. To use it try

'man command.name' it should give you help

groups - Returns with the groups that you're a member of.

env - This command sets the environment of your shell. For instance you can

change your home dir with 'env HOME=/home/blah'

at - This can be used to schedule things. Use 'at 10am' <enter> and then

enter the command you'd like it to perform at that time.

stty - This has quite a few uses, however I use it for one thing. Ever had

your backspace key produce ^H's? try "stty erase backspace"

command;command - Do you want to put multiple commands in one line? Use ;

to separate them and they'll be performed one after eachother. For instance

ls;uptime;cp blah review;./eggdrop u -m