Code Bash Frequently used bash snippets
Check memory from bash
Check access through ssh
Check open ports nmap
Copy while :;
do nmap <addres> -p443,9200,80,22 -Pn --max-rtt-timeout 60ms ;
sleep 1 ; done Check open ports lsof
Copy sudo lsof -i -P -n #or
sudo lsof -i -P -n | grep LISTEN #or
lsof -i :8000 # by port Openning port in ubuntu
Copy sudo ufw allow [PORT] If statements
Copy if [ -z STRING]
then
fi If with multiple conditions and checking lenght == 0
Copy if [ -z $VAR1 ] || [ -z $VAR2]; then
# code
fi Uninstall packages
Kill processes
Search keywords in files within a directory
Copy grep -Hrn 'search term' path/to/files Remove character in-place
Copy sed -i 's/past/future/g' file.txt Remove a specific line from file
Copy sed -i 'Ld' file.txt
# L is the linenumber to delete Add character to the beginning of the file
Copy sed -i '1s/^/future/' file.txt Remove first line from file
Create sudo user
Copy usermod -aG sudo username List omitting directory
Collect http urls from several csv into a single one
Copy cat urls.html | grep -Eo "(http|https)://[a-zA-Z0-9./?=_%:-]*" | sort -u cURL requests
Copy curl --header "Content-Type: application/json" \
--request POST \
--data '{"username":"xyz","password":"xyz"}' \
http://localhost:3000/api/login Delete history entry
history -d <line_number>
tmux
Create a new session
Copy tmux new -s sessionName
## Detached mode:
#tmux new -d -s sessionName List sessions
Attach a session
Copy tmux a -t sessionName Detach a session
Send a command to a detached session
Copy tmux send-keys -t sessionName.0 "echo 'Hello world'" ENTER Split panes for detached sessions
Copy tmux splitw -h -p 50 -t sessionName:1.0
# -p percentage of the display for the created pane
# -h or -v # horizontal/vertical splitting
## if we need to do it again we may need to select the pane we want to split first
tmux select-pane -t sessionName:1.0
tmux splitw -h -p 50 -t sessionName:1.0 Compress file
Copy tar -zcvf outputFileName folderToCompress unzip file
Copy sudo apt install unzip #(ubuntu)
unzip target_file.zip Text processing
Get specific line from file
Copy sed -n LINEp target_file awk > sed for big files
Substitute char in big file
Copy aws '{gsub(/old/,"NEW"); print}' in_file > out_file Might require LC_ALL=C at the beginning depending on in_file encoding
Get content between START and END pattern
Copy sed -n '/^CREATE TABLE/,/GO/p' Generate a password or key
Copy openssl rand -base64 32 Generate base64 encoded for text
Copy echo 'to_encode' | base64 References