50 Most Frequently Used UNIX / Linux Commands
http://www.thegeekstuff.com/2010/11/50-linux-commands/
Write a Simple Script in Shell
Write a for loop.
$ for pod_name in $(kubectl get pods -l app=swag-worker-test -o jsonpath={..metadata.name}); do; kubectl delete pod $pod_name; done
pod "swag-worker-test-67fffcdd5-5hgf3" deleted
pod "swag-worker-test-67fffcdd5-h8jgg" deleted
# you could also write multiple lines
for pod_name in $(kubectl get pods -l app=swag-worker-test -o jsonpath={..metadata.name}); do
kubectl delete pod $pod_name
done
Write a while true.
# using trap and wait will make your container react immediately to a stop request
$ bash -c "trap : TERM INT; sleep infinity & wait"
# or
$ bash -c "while true; do echo 'I am alive!'; sleep 3600; done"
or
#!/bin/bash
while true; do echo 'I am alive!'; sleep 3600; done
ref:
https://stackoverflow.com/questions/31870222/how-can-i-keep-container-running-on-kubernetes
Set Environment Variables from a File
$ export $(cat .env | grep -v ^# | xargs)
ref:
https://stackoverflow.com/questions/19331497/set-environment-variables-from-file
Switch to Another User
# the latter with "-" gets an environment as if another user just logged in
$ sudo su - ubuntu
Clear the Content of a File
$ echo -n > /var/log/nginx/error.log
ref:
https://unix.stackexchange.com/questions/88808/empty-the-contents-of-a-file
Pipeline stdout with xargs
$ find . -type f -name "*.yaml" | xargs echo
./configmap.yaml ./pvc.yaml ./service.yaml ./statefulset.yaml
$ find . -type f -name "*.yaml" | xargs -n 1 echo
./configmap.yaml
./pvc.yaml
./service.yaml
./statefulset.yaml
$ find . -type f -name "*.yaml" | xargs -n 2 echo
./configmap.yaml ./pvc.yaml
./service.yaml ./statefulset.yaml
$ redis-cli KEYS "*-*-*-*.reply.celery.pidbox" | xargs -n 100 redis-cli DEL
ref:
https://shapeshed.com/unix-xargs/
Set a Timeout for any Command
$ timeout -t 15 celery inspect ping -A app:celery -d celery@$(hostname)
Run a One-time Command at a Specific Time
at executes commands at a specified time. You may need to install the "at" package manually.
# install
$ sudo apt-get install at
# start
$ sudo atd
# list jobs
$ atq
$ at 00:05
at> echo "123" > /tmp/test.txt
$ at 00:00 18.1.2017
at> DPS_ENV=production /home/ubuntu/.virtualenvs/dps/bin/python /home/ubuntu/dps/manage.py send_emails > /tmp/send_emails.log
Press Control + D to exit at shell.
ref:
https://www.lifewire.com/linux-command-at-4091646
https://tecadmin.net/one-time-task-scheduling-using-at-commad-in-linux/
Pass Arguments to bash when Executing a script Fetched by curl
$ curl -L http://bit.ly/open-the-pod-bay-doors | bash -s -- --tags docker
ref:
https://stackoverflow.com/a/25563308/885524
https://github.com/vinta/HAL-9000
Change a File's Modify Time
$ touch -m -d '1 Jan 2006 12:34' tmp
$ touch -m -d '1 Jan 2006 12:34' tmp/old_file.txt
ref:
https://www.unixtutorial.org/2008/11/how-to-update-atime-and-mtime-for-a-file-in-unix/
Delete Old Files under a Directory
$ find /data/storage/tmp/* -mtime +2 | xargs rm -Rf
$ find /data/storage/tmp/* -mtime +2 -exec rm {} \;
ref:
http://stackoverflow.com/questions/14731133/how-to-delete-all-files-older-than-3-days-when-argument-list-too-long
Append String to a File
# append
$ echo "the last line" >> README.md
# replace
$ echo "replace all" > README.md
Rename Sub-folders
$ for f in */migrations/; do mv -v "$f" "${f%???????????}south_migrations"; done
ref:
http://unix.stackexchange.com/questions/220176/rename-specific-level-of-sub-folders
List History Commands
$ export HISTTIMEFORMAT="%Y%m%d %T "
$ history
Make Permission For A File Same As Another File
$ chmod --reference=file1 file2
Find Computer's Public IP
$ wget -qO- http://ipecho.net/plain ; echo
ref:
http://askubuntu.com/questions/95910/command-for-determining-my-public-ip
Compress and Uncompress Files
$ tar czf media-20151010.tar.gz media/
$ s3cmd put media-20151010.tar.gz s3://goeasytaxi/
# decompress
$ tar -xzf media.tar.gz
$ sudo apt-get install zip unzip
$ zip -j -r deps.zip spark_app/src/deps/
$ zip -r hourmasters.zip hourmasters/
$ scp -r -i ~/hourmasters.pem ssh [email protected]:/home/ubuntu/hourmasters.zip ~/Desktop/
# decompress
$ unzip stork.1.4.zip
$ gzip -d uwsgi.log.*.gz
$ gzip dps.201701171200.sql
$ gunzip dps.201701171200.sql.gz
Count File Lines
$ wc -l filename.txt
$ wc -l *.py
Find Files by Name or Content
$ find / -name virtualenvwrapper.sh
# 在現在的資料夾裡的全部檔案中搜尋字串，會自動搜尋子目錄
$ find . | xargs grep 'string'
$ find . -iname '*something*'
$ find *.html | xargs grep 'share_server.html'
# 搜尋當前目錄及子目錄下的含有 print() 字串的檔案
$ grep -rnw "." -e "print()"
$ grep -rnw "." -e "print()" --include=\*.py
ref:
https://stackoverflow.com/questions/16956810/how-do-i-find-all-files-containing-specific-text-on-linux
Find Directories by Name
$ find . -type d -name "*native*" -print
ref:
https://askubuntu.com/questions/153144/how-can-i-recursively-search-for-directory-names-with-a-particular-string-where
List Files by Date
$ ls -lrt
List Files Opened by a Process
$ lsof | grep uwsgi
$ lsof -i | grep LISTEN
$ lsof -i -n -P | grep LISTEN
Extract Content from a File
$ cat uwsgi.log | grep error
Display Contents of All Files in the Current Directory
$ grep . *
$ grep . *.html
List Used Ports
$ netstat -a
# TCP
$ netstat -ntlp | grep uwsgi
# UCP
$ netstat -nulp
Ping a Port
$ curl -I "10.148.70.84:9200"
$ curl -I "192.168.100.10:80"
$ sudo apt-get install nmap
$ nmap -p 4505 54.250.5.176
$ nmap -p 8000 10.10.100.70
$ nmap -p 5672 10.10.100.82
$ telnet 54.250.5.176 4505
ref:
http://stackoverflow.com/questions/12792856/what-ports-does-rabbitmq-use
Show Network Traffic and Bandwidth
$ tcpdump -i eth0
$ sudo apt-get install tcptrack
$ tcptrack -i eth0
ref:
http://askubuntu.com/questions/257263/how-to-display-network-traffic-in-terminal
List Running Processes
# show all processes
$ pstree -a
# also show pid
$ pstree -ap
# 列出前 10 個最佔記憶體的 processes
$ ps aux | sort -nk +4 | tail
# 列出 mysql 相關的 processes
$ ps aux | grep 'worker process'
$ ps aux | grep uwsgi
# 樹狀顯示
$ ps auxf
# 搜尋 process 並以樹狀結果顯示 parent process
$ ps f -opid,cmd -C python
Kill Processes
# 列出目前所有的正在記憶體當中的程序
$ ps aux
# 匹配字串
$ ps aux | grep "mongo"
# 幹掉它
$ kill PID
# kill all processes matching a name
$ sudo pkill -f runserver
Store User's Input as a Variable
$ read YOUR_VARIABLE_NAME
$ read name
# you type: vinta
$ echo $name
vinta
ref:
https://canred.blogspot.tw/2013/03/read.html
Show Terminal Size
$ stty size
$ echo $LINES && echo $COLUMNS
59 273
ref:
https://stackoverflow.com/questions/263890/how-do-i-find-the-width-height-of-a-terminal-window
