linux cheat sheet

# file:linux-cheat-sheet.sh v.1.9.5 docs at the end 

# get a nice prompt 

export PS1=" \u@\h [\d \t] [\w] $ \n\n  "

export PS1="\h [\d \t] [\w] $ \n\n  "

# aliases

# show dirs with nice time newest modified on top 

alias ll='ls -alrt --time-style=long-iso'

to_srch='what_to_srch'

to_repl='what_to_replace'

#-- srch and repl %var_id% with var_id_val in dirs in $component_name_dir_tmp

find "$dir" -type d |\

perl -nle '$o=$_;s#'"$to_srch"'#'"$to_repl"'#g;$n=$_;`mkdir -p $n` ;'

find "$dir" -type f |\

perl -nle '$o=$_;s#'"$to_srch"'#'"$to_repl"'#g;$n=$_;rename($o,$n) unless -e $n ;'

#-- srch and repl %var_id% with var_id_val in files in $component_name_dir_tmp

find "$dir" -type f -exec perl -pi -e "s#$to_srch#$to_repl#g" {} \;

find "$dir/" -type f -name '*.bak' | xargs rm -f

# find the only the uniq file names of specific file type 

find `pwd` -name '*.xml' | perl -pe 's/(.*)(\\|\/)(.*)/$3/;' | sort  | uniq -u

# how-to find in files - e.g. search by a perl regex in files and redirect the output to vim 

find `pwd` -name '*.pm' -exec grep -inHP -A 1 'sub [a-zA-Z0-9]*\s+\{' {} \; | vim -

# how-to search for a regex and build the ready open vim to found line cmds

find $dir -name '*.ext' -exec grep -nHP 'regex' {} \; | perl -ne 'm/^(.*):(\d{1,10})(.*)/g;print "vim ". "+$2 " . "$1 \n"'

# get system info

cat /proc/cpuinfo | less

cat /proc/meminfo | sort -nr -k 2 | perl -ne 'split /\s+/;printf ("%-15s %20d MB \n" , "$_[0]" , ($_[1]/1024))'

fdisk -l

# go the previous dir you where 

cd -

pushd .; popd

#how-to check opened ports with nmap

nmap -sT -O localhost

# get selinux security context

ls -al --lcontext $dir

# change the selinux security context 

chcon -vR -u system_u -r object_r -t httpd_sys_content_t $dir

# use rsync to preserve permissions

rsync -v -X -r -E -o -g --perms --acls $src_dir $tgt_dir

rsync -v -r --partial --progress --human-readable --stats $src_dir $tgt_dir

rsync -v -r --partial --progress --human-readable --stats $src_dir/$f $tgt_dir/$f

while read line_with_spaces ; do sh /path/to/script.sh "$line_with_spaces" ; done < $file_with_lines_with_spaces

# nice listing

find . -type f -exec stat -c '%n %y' {} \; | sort -n | less

# check permissions effectively 

find . -type f -exec stat -c "%U:%G %a %n" {} \; | less

export file_name_to_filter=infa-reporter

stat -c "%n %y" *.zip | perl -ne 'm/^(.*?) (.*)/g; printf "%-70s %-50s \n" , "$1" , "$2"' | sort -r -k 2 | grep -i $file_name_to_filter

# The ultimate "find in files"

find /etc/httpd/ -type f -print0 | xargs --null grep -nHP 'StartServers\s+\d' | less

for file in `find / -type f \( -name "*.pl" -or -name "*.pm" \) -exec file {} \; | grep text | perl -nle 'split /:/;print $_[0]' `; do grep -i --color -nH 'string_to_search'  $file ; done ;

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

find / -name '*bak' -print0 | xargs --null grep -nPH 'curl'

# find and replace recursively

find . -name '*.html' -print0 | xargs -0 perl -pi -e 's/foo/bar/g'

# how-to check disk space

find $dir -maxdepth 2 -type d -exec du -B M --max-depth=1 {} \; | sort -nr | less

# find all the files greather than 100 MB , sort them by the size and print their sizes 

find $dir -type f -size +2M -exec du -B M {} \; | sort -nr | less 

du -B M --max-depth 3 $dir | perl -nle 's#\s+# #g;print' | perl -ne 'm/^(.*?) (.*)/g; printf "%10s %-50s \n" , "$1" , "$2"' | sort -nr -k1 | less

# how-to search bunch of tar.gz files 

cmd="zgrep $StringToFind '{}' >> $FileToOutput"

find ${DirFindRoot} -type f  -name ${nameFilter} -print0 | xargs -0 -I '{}' sh -c "$cmd"

# disk usage of users under the /home directory in MB

export dir=/data/reseller/tmp/;

clear;du -all --block-size=1M $dir --max-depth=2 | sort -n | perl -ne '@a=split /\s+/g;$a[0]=~s/(?<=\d)(?=(?:\d\d\d)+\b)/ /g;printf "%15s %10s",$a[0],"$a[1]  \n" '

# show in megs and sort each folder

find $dir -type d -exec du --summarize -B M {} \; | sort -nr | perl -ne '@a=split /\s+/g;$a[0]=~s/(?<=\d)(?=(?:\d\d\d)+\b)/ /g;printf "%15d %10s",$a[0],"$a[1]  \n" '| less

tcpdump dst 10.168.28.22 and tcp port 22

tcpdump dst 1.2.81.2.8.212 

# record the current session via script

mkdir ~/scriptlogs

script -a ~/data/log/script/`date +%Y%m%d%H%M%S`_script.log

#/usr/bin is for normal user executables, /usr/sbin is for superuser executables, /usr/sfw is for external software (like gnu one), but provided with bundle of OS, /usr/ccs is for development utilities, usually not need for daily tasks like make, lex, yacc, sccs

# 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

echo so I redid it and saved my fingers

!345

#how-to check my history without the line numbers  

history | cut -c 8- | grep env

# how to deal with command outputs

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

#  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

# START === bash shortcuts 

# Go to the beginning of the line you are currently typing on

Ctrl + A 

# Go to the end of the line you are currently typing on

Ctrl + E

# move a word forward 

Alt + F

# move a word backwards

Alt + B

# STOP === bash shortcuts 

# 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

#display the first 20 lines of the file

head -n 20 too-long-file 

# how to restart a service initiated at startup

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

# see all the rules associated with the firewall

iptables -L -n -v --line-numbers

gunzip *file.zip

# 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

# how to kill process interactively

killall -v -i sshd

# 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 to it ) use the right arrow to

#escape from the quick search box ...

#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:

#vi /$PWD , press tab to complete the name of the current directory ,

#type the name of the file. THUS AFTER RUNNING

history | grep vim

#of course the same could be seen from the /home/username/.viinfo 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

#which version of Linux I am using

uname -a

#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

# change the owneership of the directory recursively

chown -vR user$group $dir

# perform action recursively on a set of files

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

for file in `find . -type f`;do echo cp $file ./backups/; done;

for file in `ls *.docx -1`;do echo cp $file ./backups/$file.`date +%Y%m%d%H%M%S`.docx;done;

# make Bash append rather than overwrite the history on disk:

shopt -s histappend

# henever displaying the prompt, write the previous line to disk:

PROMPT_COMMAND='history -a'

# than run the script

#how-to replace single char in file

tr '\t' ',' < FileWithTabs > fileWithCommas

# Allow access to the box from only one ip address

# create a backup file based on the timestamp on bash

cp -v fileName.ext fileName.ext.`date +%Y%m%d_%H%M%S`.bak

#check disk space

df -a -h | tail -n +2   | perl -nle 'm/(.*)\s+(\d{1,2}%\s+(.*))/g;printf "%-20s %-30s %-90s \n","$2",$3,$1' | sort -nr | less

df -a -B M | column -t | sort -nr -k 5

df  -h ***

# how-to get running processes 

ps -ef --forest 

# how-to kill misbehaving process ... you will need to adjust the -f 2 part 

# depending on the output of the ps -ef command above 

for pid in $(ps -ef | grep procToFind | perl -ne 's/\s+/ /g;print $_ . "\n";' | cut -d ' ' -f 2) ; do echo kill -9 $pid ; done ;

for pid in $(ps -ef | grep chrome | perl -ne 's/\s+/ /g;print $_ . "\n";' | cut -d ' ' -f 2) ; do echo kill -9 $pid ; done ;

#how-to create relative file paths tar package recursively fromm a dir

cd $RootDirToStartRelativePathsFrom

tar -cvzpf $pckg_to_create.tar .

# exctract tar file into cd  

tar -xvf $pck_to_exctract_to_cwd.tar

#how-to create tar archieve

tar cvf $archive_name.tar $dir/

#how-to unpack tar file

tar xvf $file

#how-to unpack gz archive

gzip -cd $file | tar -xvf -

# print line number 52

sed -n '52p' # method 1

sed '52!d' # method 2

sed '52q;d' # method 3, efficient on large files

# START === create symlink

export target_path=/cygdrive/c/var/anc

export link_path=/nz/anc

mkdir -p `dirname $link_path`

unlink $link_path

ln -s "$target_path" "$link_path"

ls -la $link_path;

# STOP === create symlink

# START === user management

#how-to add a linux group

groupadd -g "$gid" "$group"

cat /etc/group | grep --color "$group"

#how-to add an user

useradd --uid "$uid" --home-dir "$home_dir" --gid "$group" \

--create-home --shell /bin/bash "$user" \

--comment "$desc"

cat /etc/passwd | grep --color "$user"

# modify a user

usermod -a -G $group $user

# change the password for the specified user (own password)

passwd $user 

#how-to forces to change password when logging in for the first time

passwd -f login 

#change user pass to expire never 

chage -I -1 -m 0 -M 99999 -E -1 $user

# and check results 

chage -l $user

#Ei should not return anything !!!

passwd -s -a | grep NP (=No Password)

#delete an user

userdel $user

#administer the /etc/group file

gpasswd: 

# START === user management

#how-to extracts rpm packages contents

export ins=foo-bar.rpm

rpm2cpio $ins | cpio -id

#how-to extract *.tar.gz 

gzip -dc *.tar.gz | tar xvf -

cd foo-bar-dir

#--- show all installed packages

rpm -dev 

#how-to build binaries as a non-root 

./configure --prefix=$HOME && make && make install

#exctract a single file:

gzip -dc fileName.tar.gz | tar -xvf - filename

find . -name '*.log' -print | zip cipdq`date +%Y%m%d%H%M%S` -@

# find several types of files 

find . -type f \( -name "*.pl" -or -name "*.pm" \)

find / -type f | xargs grep -nH 'curl'

# print the word to find + the next 3 lines

grep -A 3 -i "theWordToFind" demo_text

find . -type f -name '*.sh' -print -exec grep -n gpg {} \;

# create a list of files

find . -print0 | xargs -r0 echo "$@"

# where am I

uname -a ; 

# who am I 

id ; 

# when this is happening 

date "+%Y.%m.%d %H:%M:%S" ; 

# reboot ... !!! BOOM BOOM BOOM !!!

shutdown -r now 

# shutdown the whole system 

shutdown -f -s 00

#how-to kill a process 

ps -aux | grep $proc_to_find

pidof $prod_to_find

kill -9 $proc_to_find

# which processes are listening on my system

netstat --tcp --listening --programs

netstat --tcp

netstat --route

#monitoring commands 

# show the top processes

top

# now press Shift + o, and choose the field to sort by 

# running processes status 

ps -auxw | less 

ps -ef | less 

#List all currently loaded kernel modules

lsmod | less 

#Displays the system's current runlevel.

/sbin/runlevel

# get the Processes attached to open files or open network ports:

lsoff | less 

# monitor the virtual memory 

vmstat 

# show the free memory

free -m

# check memory usage

egrep --color 'Mem|Cache|Swap' /proc/meminfo

#what cpu am a running

less /proc/cpuinfo

#Display/examine memory map and libraries (so). Usage: pmap pid

ps -aux | grep $MyProcToPMap

pmap   $MyprocToPMapPID

#how-to sort output by a delimited by single delimiter column 

# in this example the - char is used for delimiter , the output is 

# by their sending sequence , use proper file naming convention files 

# ls -1 gives us:

# fileBeginningTillFirstDelimiter-TheColumnToSortBy-TheRestFromTheFileNameDelimiter

ls -1 | awk -F1 'BEGIN {FS="-"};{print $2 "¤" $1 "-" $2 "-" $3 }' | sort -nr | cut -d ¤ -f 2,5 

# the same approach with perl

ls -1 | perl -p -i -e 's/^([^\-]*)(\-)([^\-]*)(\-)([^\-]*)/$3¤$1.2.8$4$5/g' | sort -nr | cut -d ¤ -f 2,5  

# how-to use sftp with remoteUserName having publicIdentity of PublicIdentityUserName

sftp -v -o "IdentityFile /var/www/.ssh-id/PublicIdentityUserName" \

-o "UserKnownHostsFile /var/www/.ssh-id/known_hosts" remoteUserName@ServerHostNameOrIpd

ssh -v -o ServerAliveInterval 300 -o ServerAliveCountMax 1 

# ==================================================================

# START Jobs control 

# start some very long lasting command 

find / -name '*.crt' | less 

# now press Ctrl + Z 

# the terminal says "Jobs stopped"

# now check the open jobs 

jobs

# you should see something like 

# [1]+  Stopped                 find / -name '*.crt' | less

# now put the job in the background and start working on something else by Ctrl + Z 

bg 1

# run the next command 

# how-to copy file via scp by using specificy identity

scp -v -o "IdentityFile /home/userName/.ssh/id_rsa" /data/path/dir/* \

userName@ServerHostName.Domain.com:/Server/Target/Dir/

# now again stop the job first by Ctrl + Z 

# check again the running jobs 

jobs 

# use should see the both of the jobs started 

# now put the first on in the forground 

fg 1

# Repeat that several times untill you get it ; ) !!!

# start command in the background

command1 &

# how-to redirect STDERR STDOUT to log file 

sh $script.sh | tee 2>&1 $log_file

# how-to start a separate shell 

( command &) &

# get the STDERR and STDOUTPUT 

output=$(command 2>&1)

# how-to detach an already started job from the terminal

jobs 

disown -h %1

# how-to start 

nohup log_script.sh &

# run a proc every 2 seconds

watch -n 2 "$cmd_to_run"

# END Jobs control 

# ==================================================================

nicedate=`date +%Z-%Y%m%d%H%M%S`

# kill a process by name 

ProcNameToKill=listener-nat_filter_caller.sh

# ps -ef | grep wget | perl -ne 'split /\s+/;print "kill $_[7] with PID $_[1] \n";`kill -9 $_[1];`'

ps -ef | grep $ProcNameToKill | grep -v "grep $ProcNameToKill" | \

perl -ne 'split /\s+/;print "kill $_[7] with PID $_[1] \n";`kill -9 $_[1];`'

# how-to display human readable file sizes on systems with stupid du

# of course you would have to have perl next_line_is_templatized

find $dir -type f -exec du -k {} \; | \

perl -ne 'split /\s+/;my $SizesInMegs=$_[0]/1024; \

printf ( "%10d %10s \n" , "$SizesInMegs" , "MB $_[1]")' | sort -nr 

export dir=/

echo sizes in MB

find $dir -type f -exec du -k {} \; | \

perl -ne 'split /\s+/;my $SizesInMegs=$_[0]/1024; \

printf ( "%10d %-100s \n" , "$SizesInMegs" , "$_[1]")' | sort -nr | more

#who has been accessing via ssh 

for file in `find /var/log/secure* | sort -rn` ; do grep -nHP 'user' $file ; done; | less

#print files recursively 

dir=/opt/

clear;find $dir -type f -exec ls -alt --time-style=long-iso --color=tty {} \; | \

perl -ne 'split(/\s+/);printf ( "%10s %2s %-20s \n" , "$_[5]", "$_[6]", "$_[7]") ; ' | sort -nr

#how-to print relative file paths to /some/DirName with perl one liner 

find /some/DirName -type f | perl -ne 'split/DirName\//;print "$_[1]"  '

# see nice dir recursively listing newest first

dir=/tmp

find $dir -name '*.tmp' -exec ls -alt --time-style=long-iso --color=tty {} \; | \

perl -ne 'split/\s+/;print "$_[5] $_[6] $_[7] \n" ;' | sort -nr | less

# how-to sort files based on a number sequence in their file names

# list dir files , grap a number from their names , print with NumberFileName, sort , \

# print finally the names without the Number but sorted 

 ls -1 | perl -ne 'm/(\d{8})/; print $1 . $_ ;' | sort -nr | perl -ne 's/(\d{8})//;print $_'

# START === how-to implement public private key authentication 

# create pub priv keys on server

# START copy 

ssh-keygen -t rsa

# copy the rsa pub key to the ssh server

scp ~/.ssh/id_rsa.pub $ssh_user@$ssh_server:/home/$ssh_user/

# STOP copy  

# Hit enter twice 

# START copy 

cat id_rsa.pub >> ~/.ssh/authorized_keys

cat ~/.ssh/authorized_keys

chmod 0600  ~/.ssh/authorized_keys

ls -al ~/.ssh/authorized_keys

rm -fv ~/id_rsa.pub

# STOP COPY

# START copy 

ssh-keygen -t dsa

# STOP copy  

# Hit enter twice 

# START copy 

cat id_dsa.pub > ~/.ssh/authorized_keys2

cat ~/.ssh/authorized_keys2

chmod 644  ~/.ssh/authorized_keys2

# STOP COPY

# STOP === how-to implement public private key authentication

# show me a nice calendar 

cal -m -3

# START === how-to enable port forwarding or tunnelling

export local_port=6000

export remote_port=6000

export ssh_user=type_here_ssh_user

export ssh_server=type_here_the_hostname

export db_server=type_here_the_db_hostname

#[-L [bind_address:]port:host:hostport] 

ssh -L localhost:$local_port:$db_server:$remote_port $ssh_user@$ssh_server

# STOP === how-to enable port forwarding or tunnelling

# START === cron scheduling 

#edit the crontab

crontab -e

# view the crontab

crontab -l 

# * * * * * command to be executed

# - - - - -

# | | | | |

# | | | | +- - - - day of week (0 - 6) (Sunday=0)

# | | | +- - - - - month (1 - 12)

# | | +- - - - - - day of month (1 - 31)

# | +- - - - - - - hour (0 - 23)

# +--------------- minute

# STOP === cron scheduling 

#how-to limit the resources of the current session 

help ulimit 

nameTerminal $USER@`hostname`_ON_`pwd`__at__`date +%Y-%m-%d_%H:%M:%S`

# how-to send via e-mails the files of a dir with mailx

export dir=`pwd`

export attachments=$(find $dir -type f| perl -ne 'print "-a $_"'| xargs)

echo $attachments | mailx $attachments -s "$dir files" $MyEmail

mailx $(find $dir -type f| perl -ne 'print "-a $_"'| xargs) -s "$fir files" $MyEmail < `echo $(find $dir -type f| perl -ne 'print "-a $_"'| xargs)`

# change user password expiry information

for usr in "$userlist"; do sudo passwd $usr; sudo chage -E -1 -M -1 $usr; sudo chage -d0 $usr; done

#how-to check the file encoding

file_encoding=$(file -bi $file | sed -e 's/.*[ ]charset=//')

# Purpose: 

# to provide a simple cheat sheet for most of the Linux related commands

# usefull web sources: http://www.cyberciti.biz

# how-to add new repository to yum

yum-config-manager --add-repo http://www.example.com/example.re

#how-to view installed packages with yum on RH

yum list installed | less

yum clean all 

yum -y install perl

# update all but the linux kernel packages

yum -y --exclude=kernel\* update

/nz/kit/sbin/sendMail -dst first.last@company.com -msg "subject line" -bodyTextFile $outfile -removeFile

# start putty with preloaded session on windowz

cmd /c start /max putty -load username@hostname

#how-to install only specific package from cygwin via cmd

setup-x86_64.exe -n -q -s http://cygwin.mirror.constant.com -P %package_name%

c=0

cat "$list_file" |   { while read -r jira_issue ; do c=$((c+1)) ; test $c -eq 5 && sleep $c && export c=0 ; ( sh /maintenance/ip/sfw/sh/jira --action progressIssue --issue $jira_issue --step 41 )& done }

# how-to enable pw auth on apache

pw_file=/var/www/html/maint/.htpasswd

user=mmt

htpasswd -c $pw_file $user

#how-to change the access and mofication timestamp

ts='201401181205.09'

touch -a -m -t "$ts" "$file"

# how-to install packages on ubuntu

apt-get -y install $package_name

# howto install packages on red-hat

yum install $package_name

#v1.9.5 how-to use text editor for longer command typing

set EDITOR=vim

#Ctrl+X,E

#v1.9.5 - how-to get variations by curly expansions

echo {A,B,C}{0,1,3}

#useful sources - hint: google site:<site>

#http://www.cyberciti.biz

#http://www.yolinux.com/TUTORIALS/LinuxTutorialSysAdmin.html#MONITOR

#http://www.commandlinefu.com/commands/browse/sort-by-votes

#http://wiki.bash-hackers.org/

#

#==========================================================

# VersionHistory

#==========================================================

# 1.9.5 --- 2014-23-04 22:37:07 --- ysg --- Ctrl+X,E trick

#

# eof file:linux-cheat-sheet