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Shell scripting hacks!!!!
# Version : 1.0
# Author : Nitish Bhardwaj
# Description : This Script file contains some shell script quick hacks.
#Check below links to get basics
#to check open/closed port on a remote machine
nc -zw3 5432 && echo "opened" || echo "closed"
#to check ip of devices connected in local network
#Method :1
arp -a | grep 192.168.1. | grep ether
#Method :2
for i in `seq 1 254`; do ping -c 1 -q 192.168.1.$i &; done
#to check internet connectivity
sudo nm-tool | grep "State: connected" | wc -l
#'1' means connected and '0' means not connnected
#to check ip address
/sbin/ifconfig eth0 | grep 'inet addr' | cut -d: -f2 | awk '{print $1}'
#to check OS distribution
lsb_release -i -s
#LSB means (Linux Standard Base)
#to check OS distribution and version
lsb_release -d -s
#to copy to remote machine using scp connecting it without RSA key authorization
sshpass -p "$password" scp -o StrictHostKeyChecking=no -o UserKnownHostsFile=/dev/null $algo_script "$username"@"$ip":./
#to pass a variable to remote machine using ssh
sshpass -p "$password" ssh -t "$username"@"$ip" 'export MYVAR='"'$toAlgo'"';sh'
#to run a script on remote machine using ssh even after disconnection
sshpass -p "$password" ssh -x "$username"@"$ip" 'sh'
#to pass a variable and execute multiple scripts to remote machine using ssh
sshpass -p "$password" ssh -t "$username"@"$ip" 'export MYVAR='"'$password'"';
sh;echo "$password" | sudo -S rm -rf package;
echo "$password"|sudo -S sh;echo "$password" | sudo -S rm -rf'
# to split a string based on a delimiter
#spliting $first based on delimiter '.' and storing the 4th part to pi_ip
pi_ip=$(echo $first | awk '{split($0,a,"."); print a[4]}')
#to run installation and output to terminal as well as write to log file
sudo apt-get install $some_package | tee -a writer.log
#to run installation/any command and silent the console messages or warning
sudo apt-get install $some_package 2>/dev/null
#to check python package $1 with version $2
temp=`python -c "import "$1"; print "$1".__version__== '$2'"`
#Grep (an acronym for “Global Regular Expression Print”)
#to find and replace some string in all the files in a folder
grep -rl "old_string" /home/path/*.files | xargs sed -i "s/old_string/new_string/g"
#to find some string along with the context
grep -r "some_string" /home/path/folder
#to extract files from ISO image
sudo mount -o loop <image>.iso /mnt/iso
#to show byte information of an ISO and truncate ISO size
sudo fdisk -l <image>.iso
sudo truncate --size=$[(31116287+1)*512] <image>.iso
#'31116287' is the last filled bit in the disk; check from the results of fdisk
#to check storage devices
df -h
#Taking ISO image of SD card
sudo dd if=/dev/mmcblk0 of=/home/nitish/Desktop/jasper_complete.iso
#Burning SD card with ISO files
sudo dd if=/home/nitish/Desktop/pi_iso/latest_228.iso of=/dev/mmcblk0
#Expanding the SD Card
sudo raspi-config
#to extract a running process and kill the process
kill -9 $(ps -ef | grep 'processX' | grep -v grep | awk 'NR==1' | awk '{split($0,a," "); print a[2]}')
kill -9 `ps aux|grep mjpg_streamer|awk '$17== "HumanTracking.jpg" {print $2}'`
#to extract multiple instances of a running process and kill the processes
while [ $(ps -ef | grep 'redis-server' | grep -v grep | wc -l) -ge 1 ]
echo $password | sudo -S kill -9 $(ps -ef | grep 'redis-server' | grep -v grep | awk 'NR==1' | awk '{split($0,a," "); print a[2]}')
#to read from a file line by line separated by Internal Field Separator ':'
while IFS=: read -r f1 f2
echo f1 + f2
done < $config_file
#to launch GUI firefox from remote machine
sshpass -p "$password" ssh -X "$username"@"$ip" 'export DISPLAY=":0";firefox ""'
#to empty a file without deleting the file
cat /dev/null > temp.txt
sed -i '1icolumn1, column2, column3' testfile.csv
#The "1i" command tells sed to go to line 1 and insert the text there.
#The -i option causes the file to be edited "in place"
#and can also take an optional argument to create a backup file, for example
sed -i~ '1icolumn1, column2, column3' testfile.csv
#would keep the original file in "testfile.csv~".
#If you want to delete lines 5 through 10 and 12:
sed -e '5,10d;12d' file
#This will print the results to the screen. If you want to save the results to the same file:
sed -i.bak -e '5,10d;12d' file
#This will back the file up to file, and delete the given lines.
sed -n '4p' file
#it will return the text at line number 4
#to kill an open port, say 3000
sudo kill -9 $(sudo lsof -t -i:3000)
#to set up a cron job
#to check all the installed packages
dpkg -l
#to find number of characters in a variable
x="This is a test. S"
grep -o "[s|S]" <<<"$x" | wc -l
#output : 4
#to split and combine a big size file
#Lets says I have an image and its too big (10MB). All I do is:
split --bytes=1M /path/to/image/image.jpg /path/to/image/prefixForNewImagePieces
#and then to put it together I use cat:
cat prefixFiles* > newimage.jpg
#Arithmetic in bash is done with $ and double parentheses:
echo "$(($num1+$num2))"
#Or $ and square brackets:
echo "$[$num1+$num2]"
#You can assign from that (sans echo). There is also expr:
echo `expr "$num1" + "$num2"`
#scale=4 tells bc to use four decimal places
echo 'scale=4;3.1415+9.99' | bc
#Using the find command to recursively delete temp files
find -name *~ -exec rm -rf {} \;
#to check video length
for i in $(pwd)/*; do echo $i; ffmpeg -i $i 2>&1 | grep Duration | cut -d ' ' -f 4 | sed s/,//; done
#to check for images files from terminal and do some ops
for i in "$(pwd)"/*.jpg; do grep -n $(basename $i) ../training-labels | cut -d ':' -f 2| tee -a tagging.log; done;
#to resize image
find training-images/ -name "*.jpg" -exec convert {} -resize 128x128! {} \;
#one liner script for a scheduler
while true; do mintime=$(date +"%M"); secondtime=$(date +"%S");if [ "$mintime" -eq "48" ] && [ "$secondtime" -eq "50" ];then echo $(date); break; else echo "hi"; fi; done;
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