$ pwd # print working directory ls -la # list all files with details cd /path/to/dir # change directory cd .. # go up one level cd - # go back to previous directory find . -name "*.py" # find files by name pattern locate filename # find file quickly (uses indexed db) pwd # print working directory ls -la # list all files with details cd /path/to/dir # change directory cd .. # go up one level cd - # go back to previous directory find . -name "*.py" # find files by name pattern locate filename # find file quickly (uses indexed db) pwd # print working directory ls -la # list all files with details cd /path/to/dir # change directory cd .. # go up one level cd - # go back to previous directory find . -name "*.py" # find files by name pattern locate filename # find file quickly (uses indexed db) cp source dest # copy file cp -r source dest # copy directory recursively mv source dest # move or rename rm file # -weight: 500;">remove file rm -rf dir # -weight: 500;">remove directory (DANGER — no undo) mkdir -p a/b/c # create nested directories touch file # create empty file or -weight: 500;">update timestamp ln -s target link # create symbolic link cp source dest # copy file cp -r source dest # copy directory recursively mv source dest # move or rename rm file # -weight: 500;">remove file rm -rf dir # -weight: 500;">remove directory (DANGER — no undo) mkdir -p a/b/c # create nested directories touch file # create empty file or -weight: 500;">update timestamp ln -s target link # create symbolic link cp source dest # copy file cp -r source dest # copy directory recursively mv source dest # move or rename rm file # -weight: 500;">remove file rm -rf dir # -weight: 500;">remove directory (DANGER — no undo) mkdir -p a/b/c # create nested directories touch file # create empty file or -weight: 500;">update timestamp ln -s target link # create symbolic link cat file # print entire file less file # scroll through file (q to quit) head -20 file # first 20 lines tail -f file # follow file as it grows (logs) wc -l file # count lines grep "pattern" file # search for pattern grep -r "pattern" dir # search recursively nano file # simple terminal editor vim file # advanced editor (:q! to quit) cat file # print entire file less file # scroll through file (q to quit) head -20 file # first 20 lines tail -f file # follow file as it grows (logs) wc -l file # count lines grep "pattern" file # search for pattern grep -r "pattern" dir # search recursively nano file # simple terminal editor vim file # advanced editor (:q! to quit) cat file # print entire file less file # scroll through file (q to quit) head -20 file # first 20 lines tail -f file # follow file as it grows (logs) wc -l file # count lines grep "pattern" file # search for pattern grep -r "pattern" dir # search recursively nano file # simple terminal editor vim file # advanced editor (:q! to quit) chmod 755 script.sh # rwxr-xr-x (owner full, others read+execute) chmod +x script.sh # make executable chown user:group file # change owner and group umask 022 # set default permissions mask chmod 755 script.sh # rwxr-xr-x (owner full, others read+execute) chmod +x script.sh # make executable chown user:group file # change owner and group umask 022 # set default permissions mask chmod 755 script.sh # rwxr-xr-x (owner full, others read+execute) chmod +x script.sh # make executable chown user:group file # change owner and group umask 022 # set default permissions mask ps aux # list all running processes ps aux | grep nginx # find specific process top # real-time process monitor (q to quit) htop # prettier top (-weight: 500;">install separately) kill 1234 # terminate process by PID kill -9 1234 # force kill (SIGKILL) pkill -f pattern # kill by name pattern bg # resume suspended job in background fg # bring background job to foreground jobs # list background jobs ps aux # list all running processes ps aux | grep nginx # find specific process top # real-time process monitor (q to quit) htop # prettier top (-weight: 500;">install separately) kill 1234 # terminate process by PID kill -9 1234 # force kill (SIGKILL) pkill -f pattern # kill by name pattern bg # resume suspended job in background fg # bring background job to foreground jobs # list background jobs ps aux # list all running processes ps aux | grep nginx # find specific process top # real-time process monitor (q to quit) htop # prettier top (-weight: 500;">install separately) kill 1234 # terminate process by PID kill -9 1234 # force kill (SIGKILL) pkill -f pattern # kill by name pattern bg # resume suspended job in background fg # bring background job to foreground jobs # list background jobs df -h # disk free (human-readable) du -sh dir # directory size summary du -sh * | sort -h # size of each item, sorted mount # show mounted filesystems lsblk # list block devices df -h # disk free (human-readable) du -sh dir # directory size summary du -sh * | sort -h # size of each item, sorted mount # show mounted filesystems lsblk # list block devices df -h # disk free (human-readable) du -sh dir # directory size summary du -sh * | sort -h # size of each item, sorted mount # show mounted filesystems lsblk # list block devices ping host # test connectivity -weight: 500;">curl -I url # fetch headers only -weight: 500;">curl -s url | jq # fetch JSON and pretty-print -weight: 500;">wget url # download file ssh user@host # connect to remote server scp file user@host:path # copy file to remote netstat -tlnp # listening ports ss -tlnp # modern alternative to netstat lsof -i :3000 # what's using port 3000 ping host # test connectivity -weight: 500;">curl -I url # fetch headers only -weight: 500;">curl -s url | jq # fetch JSON and pretty-print -weight: 500;">wget url # download file ssh user@host # connect to remote server scp file user@host:path # copy file to remote netstat -tlnp # listening ports ss -tlnp # modern alternative to netstat lsof -i :3000 # what's using port 3000 ping host # test connectivity -weight: 500;">curl -I url # fetch headers only -weight: 500;">curl -s url | jq # fetch JSON and pretty-print -weight: 500;">wget url # download file ssh user@host # connect to remote server scp file user@host:path # copy file to remote netstat -tlnp # listening ports ss -tlnp # modern alternative to netstat lsof -i :3000 # what's using port 3000 sed 's/old/new/g' file # replace all occurrences awk '{{print $1}}' file # print first column sort file # sort lines sort -u file # sort and deduplicate uniq -c file # count occurrences cut -d',' -f1 file # extract column 1 from CSV tr '[:lower:]' '[:upper:]' # convert case sed 's/old/new/g' file # replace all occurrences awk '{{print $1}}' file # print first column sort file # sort lines sort -u file # sort and deduplicate uniq -c file # count occurrences cut -d',' -f1 file # extract column 1 from CSV tr '[:lower:]' '[:upper:]' # convert case sed 's/old/new/g' file # replace all occurrences awk '{{print $1}}' file # print first column sort file # sort lines sort -u file # sort and deduplicate uniq -c file # count occurrences cut -d',' -f1 file # extract column 1 from CSV tr '[:lower:]' '[:upper:]' # convert case tar -czf archive.tar.gz dir # create gzipped tarball tar -xzf archive.tar.gz # extract gzipped tarball gzip file # compress single file gunzip file.gz # decompress zip -r archive.zip dir # create zip tar -czf archive.tar.gz dir # create gzipped tarball tar -xzf archive.tar.gz # extract gzipped tarball gzip file # compress single file gunzip file.gz # decompress zip -r archive.zip dir # create zip tar -czf archive.tar.gz dir # create gzipped tarball tar -xzf archive.tar.gz # extract gzipped tarball gzip file # compress single file gunzip file.gz # decompress zip -r archive.zip dir # create zip uname -a # kernel info whoami # current user who # who is logged in uptime # how long system has been up free -h # memory usage date # current date/time history # command history !! # re-run last command !$ # last argument of previous command uname -a # kernel info whoami # current user who # who is logged in uptime # how long system has been up free -h # memory usage date # current date/time history # command history !! # re-run last command !$ # last argument of previous command uname -a # kernel info whoami # current user who # who is logged in uptime # how long system has been up free -h # memory usage date # current date/time history # command history !! # re-run last command !$ # last argument of previous command