Linux cheat sheet

#Hint , if you copy paste from this document to putty write first echo and than paste ..

#get the help in better format

#if the man is full of references to files

man commandToFindHelpAbout | col -b >/var/man/mancommandToFindHelpAbout.man.txt

echo create a backup file based on the timestamp on bash

cp fileName.ext fileName.ext.`date +%Y%m%d%H%M%S`.bak

alias ls="ls -a -X -1 --color=tty"

alias dir="ls -ba"
alias cls="clear"
alias deltree="rm -r"
alias move="mv"
ls -al | more
#Work with the history

#-- where I have been lately ?

history | grep cd

#take the last 5 commands for faster execution to the temp execution script

tail -n 5 /root/.bash_history >> /var/run.sh

#I saw the command cd /to/some/suching/dir/which/was/very/long/to/type so I redid it and saved my fingers

!345

history >history.txt ---- echo the last 1000 commands into a history.txt file

#send that file to myself

cat history.txt | mail -s "test file sending" -c mail1@com yordan.georgiev(boom)gmail.com

#remove all trealing spaces from the history file works for TextPad

^([ ]*)([0-9]*)(.*)$

\3 --- replace with the pure commands

history | gawk -F1 'BEGIN {FS=" "};{print $2 , $3}' | less

#display the history withouth the line numbers ...

history | perl -i -pe 's/^([ ]*)([0-9]*)(.*)$/$3/gi'





vim fileName anotherFile

#how to deal with command outputs

command | filtercommand > command_output.txt 2>errors_from_command.txt

#Hint after the less filter pressing s will prompt you for saving the output to a file ...

# find all files and folders containing the word linux and pipe it to the less for easier viewing

find / -name "linux" | less

# find the files having os somewhere in their names and only those having linux

find . -name '*os*' | grep linux | less

#find all xml type of files and display only the rows having wordToFindInRow

find . -name '*.xml' -exec cat {} \;| grep wordToFindInRow | less

#The ultimate "find in files" in Linux

find / -name '*bash*' -exec grep -nH tty {} \;

# or even faster , be aware of "funny file names xargs -0

find / -name '*bak' | xargs grep -nH tty

Ctrl + A --- Go to the beginning of the line you are currently typing on
Ctrl + E --- Go to the end of the line you are currently typing on

#how-to mount an usb stick

#remember to change the path other wise you will get the device is busy errror

mkdir /mnt/usbflash
mount /dev/sdb1 -t vfat /mnt/usbflash

umount /mnt/usbflash



head -n 20 tooLongFile -- display the first 20 lines of the file

#change the uggly prompt

vim /etc/bashrc

PS1="\u@\h \t \w\n\\$ "

#how to restart a process initiated at startup

/etc/rc.d/init.d/sendmail start | stop | status | restart

#see all the rules associated with the firewall

iptables -L -v

gunzip *file.zip

tar -xvf file.tar

To access the server download winscp.exe:

::start winscp with a stored session

winscp oracle@192.168.255.12

#To start remote session click on the putty screen , configure putty settings to pull full screen with alt + Enter

#right click on the title bar , settings , change the font , copy paste from and to the terminal window text

#how to ensure the sshd daemon is running

ps -ef | grep sshd

#User and group management

useradd -p winscppass -r winscp -d /home/winscp --- to add a user with specifig home directory name and pass

luserdel winscp --- delete the user

gpasswd: administer the /etc/group file
groupadd: Create a new group
groupmod: Modify a group
groupdel: Delete a new group

useradd: Create a new user or update default new user information
usermod: Modify a user account
userdel: Delete a user account and related files

#how to kill process interactively

killall -v -i sshd

#disk usage of users under the /home directory

du --max-depth=1 /home | sort -n -r



#the most efficent way to search your history is to hit Ctrl R and type the start of the command. It will autocomplete as soon as there’s a match to a history entry, then you just hit enter. If you want to complete the command (add more stuff to it ) use the right arrow to escape from the quick search box ...

How to install Perl modules

gzip -dc yourmodule.tar.gz | tar -xof -

perl Makefile.PL

make test

make install

How to see better which file were opened , which directories were visited

type always the fullpath after the vi - use the $PWD env variable to open files in the current directory , thus after opening the file after:

vim /$PWD , press tab to complete the name of the current directory , type the name of the file

thus after

history | grep vim



the full list of opened files is viwed .

of course the same could be seen from the /home/username/.viminfo file /files

where to set the colors for the terminal (if you are lucky to have one with colors; )

/etc/DIR_COLORS

open a file containing "sh" in its name bellow the "/usr/lib" directory

:r !find /usr/lib -name *sh*

go over the file and gf

uname -a --- which version of Linux I am using

rmp -qa --- show all installed packages

passwd [username] --- change the password for the specified user (own password)



How to copy paste text in the putty window from client to server - click the right button of your pointing device

How to copy paste text from the putty window from server to client - right-click the window title and select copy all to Clipboard.

To restart a service

service sshd restart

service --status-all --- show the status of all services



chown -R root:nortel Directory

#perform action recursively on a set of files

find . -name '*.pl' -exec perl -wc {} \;

$ for file in *
> do cp $file $file.bak
> done

$ for file in `ls -R` ; do cp $file $file.bak; done

#make Bash append rather than overwrite the history on disk:
shopt -s histappend

#Whenever displaying the prompt, write the previous line to disk:
PROMPT_COMMAND='history -a'



gpm -- general "cut and paste" server