Shell Cheatsheet

grep pattern files - search for pattern in files
grep -r pattern dir - search recursively for pattern in dir
command | grep pattern - search for for pattern in in the output of command
find . -name "*.js" - find all file whose extension is js in current directory

create 10 files

  for ((i=0; i<10; i++)); do
      touch test_$i.txt
  done

find . -name "*.pyc"|xargs rm - remove (rm) all file matching the pattern (filename *.pyc)
find . -name "pattern" | xargs rm -rf - remove all file/dir matching the pattern
find . -name "*.c" -print0 | xargs -0 rm -rf - correctly deal with filenames containing space
find . -name '*.sh' | xargs grep "SBATCH" - find all occurence of “SBATCH” in files that match the pattern
echo a b c | xargs cmd - execute cmd 1; cmd 2; cmd 3
echo a b c | xargs mkdir - create three dir a b c
Basics (c.f. link)
- xargs - when you type xargs without any argument, it will prompt you to enter the input through stdin
- echo a b c | xargs -d\n - specify delimiter using -d option
- echo a b c | xargs -n 2 - display only 2 items per line in the xargs output
- echo a b c | xargs -p -n 2 - prompt before execution
- xargs --show-limits - display system limits on xargs

ls - directory listing
ls -al - formatted listing with hidden files
cd dir - change directory to dir
cd - change to home
pwd - show current directory
readlink -f params.json - show path of the file
mkdir dir - create direcotry dir
rm file - delete file
rm -rf dir - remove directory dir
ln -s file link - create symbolic link ‘link’ to file
touch file - create or update file
sed -i 's/word1/word2/g' input.file - replace word1 with word2 in input file
cat > file - place standard input into file
less file - output the contents of the file
head file - output first 10 lines of file
tail file - output last 10 lines of file
tail -f file - output contents of file as it grows
chmod octal file - change permission of file
- 4 - read (r)
- 2 - write (w)
- 1 - execute (x)
- order: owner/group/world
chmod 777 files - rwx for everyone
chmod 755 files - rw for owner, rx for group/world

ping host - ping host ‘host’
whois domain - get whois for domain
dig domain - get DNS for domain
dig -x host - reverse lookup host
wget file - download file
wget -c file - continue stopped download
wget -r url - recursively download files from url
wget --load-cookies /tmp/cookies.txt "https://docs.google.com/uc?export=download&confirm=$(wget --quiet --save-cookies /tmp/cookies.txt --keep-session-cookies --no-check-certificate 'https://docs.google.com/uc?export=download&id=FILEID' -O- | sed -rn 's/.*confirm=([0-9A-Za-z_]+).*/\1\n/p')&id=FILEID" -O FILENAME && rm -rf /tmp/cookies.txt download gdrive files

Cheatsheets