My Software Universe Cheat Sheet

List of useful commands for all technologies I regularly use.

Content:

• JVM
• Shell
• Tmux
• AWS CLI

JVM

Show running Java processes:

jps

Show thread stack trace for Java process:

jstack <PID>

Every 500ms print GC cause of the running JVM process

jstat -gccause <PID> 500ms

Remote debugging

java -agentlib:jdwp=transport=dt_socket,server=y,address=8000,suspend=n

Shell

misc

Show all process as a tree

ps ufax

Show processes listening on ports

sudo netstat -lneutp

Watch file size of the file

watch du -sh file.txt

Find text in files

find . -name "*.txt" -exec grep -n -H "text" {} \\;

netcat

listen on specific port and forward output to the file

nc -l 5555 > output.raw

connect to host and port and send some text

nc localhost 5555
> Hello World!

tcpdump

Sniff communication on localhost interface (lo) and port 5555 and write it to the file

tcpdump -i lo -w recording.pcap port 5555

awk

Remove empty lines from a file

awk 'length($0) > 0 {print $0}' file_with_blanks > new_file_wo_blanks

Print first column but wrap value in double quotes

head file.csv | awk -F\; '{print "\x22"$1"\x22"}'

sed

Escape quotes in the file $f

sed 's/\"/\\\"/g' $f

Tmux

Set start directory for current tmux session Press Ctrl+B, : and then write attach -c /path/to/start/directory

Rename current session: Ctrl+B, $

AWS CLI

List all instances with the project tag set to <value>

aws ec2 describe-instances --filters "Name=tag:Project,Values=<value>" --output text --query 'Reservations[*].Instances[*].[ImageId,State.Name,PublicIpAddress,Tags[*]]' | column -t

Peter Belko

Software Engineer, Geek, Coffee lover

Tweet Share