Some commonly used Linux commands.
View the number of files in a directory
ls -l | wc -l
View the number of files in a directory and its subdirectories
find . -type f | wc -l
View the number of lines in a file
wc -l file.txt
Find file content and display a few lines before and after
grep -C 5 'hello' file.txt
Find the first few lines of a file
head -n 100 file.txt
Find the last few lines of a file
tail -n 100 file.txt
tail -f file.txt
tail -f -n 50 file.txt
View text files page by page
less file.txt
- Space or Enter or Down Arrow to scroll down
- b to scroll up
- q to quit
- /keyword to search down
- ?keyword to search up
more, can only scroll down
more file.txt
- Space or Enter to scroll down
- q to quit
- /keyword to search down
cat through pipe for pagination
cat file.txt | less
cat file.txt | more
Split files
Split by size:
split -b 100m -d --additional-suffix=.txt file.txt part_
Split by number of lines:
split -l 10000 -d --additional-suffix=.txt file.txt part_
Find the process on port 8082 and kill it
lsof -ti :8082 | xargs kill -9
No need to find the process by port first, then kill by PID
Directly kill Java-related processes
pkill -9 java
View ports
netstat -ntlp
lsof -i:8080
Test if a port is open
telnet example.com 8082
Check disk space
df -h # Check disk space for all paths
du -sh * # Check size of all files or directories in the current directory
du -sh . # Check total size of the current directory
Check memory usage
free -h
free -s 2 # Refresh every two seconds
free -s 2 -c 5 # Refresh 5 times
Check GPU memory usage
nvidia-smi
watch -n 1 nvidia-smi
Compression/Decompression usage
zip archive.zip file1.txt file2.txt
zip -r myfolder.zip myfolder/ # Compress entire directory
zip -e secret.zip demo.txt # Encrypt
zip -u existing.zip newfile.txt
Decompress:
unzip archive.zip
-d # Specify directory
-l # View only without decompressing
-o # Overwrite
-x # Exclude files
curl test HTTP requests
curl -X POST \
-H "Content-Type: application/json" \
-H "Authorization: Token abc123" \
-u elastic:123456 \
-d '{"query": {"match": {"_id": "584338" }}}' \
'http://localhost:8082/test/_search'
Just a simple record for reference.