fc- Update last executed command<command> | tee <file_name>- Execute command and print output to stdout as well as file_name
echo $0- Check which shell is running nowchsh -s /bin/bash- To set bash as default shell forcurrent (logged-in)usersudo chsh -s /bin/bash- To set bash as default shell forrootuser
Close and open terminal again to see the effect. Note: shell should be in /etc/shells list for this to work
/bin/bash- Run bash shell temporarily in open terminal session/bin/zsh- Run zsh temporarily in open terminal session
ls -lh- To see human readable logical space usagels - ks- To see physical space usage
du -h- To see disk space usage (physical)
tree .# prints all the subdirectories.tree -L 4# prints up to 4 directories.tree -I 'test* |docs|bin|lib'# ignores the directories - test docs bin lib.tree -P '.sh' --prune# lists all the .sh files and --prune will remove empty directories from getting printed.
In the output of first command look for line containing ls and without containing al. Here -v reverse the normal grep functionality.
history | grep ls | grep -v al- Used to test an expression -
test 100 -lt 99 && echo "Yes." || echo "No."- This will print "No." bcz expression is false. - Used to check existence of files and more -
test -e test-security-gateway.log; echo $?- This will print 0 if the file exists.
Copy files from one computer to another
- Copy files securely from one computer to another (secure, encrypted)
scp <file_to_copy> <machine_to_copy_file-to>:<location_inside_machine_to_copy_file_to>- E.g.,
scp something.jar sys01.net: - If location is not specified in target machine, then the file will be copied to
$HOMEdirectory
- E.g.,
Advanced copying tool
ps aux | grep <keyword>ps -ef | grep <keyword>
kill -9 <PID>- Here 9 is the signal number which isKILLsignal (see below for desc.).- Same as
kill -KILL <PID>andkill -SIGKILL <PID>
- Same as
kill <PID>-TERMsignal is send as that's the default
TERM- an application will be able to terminate, i.e. properly run a shutdown routineKILL- the applications is stopped and killed immediately (which could lead to data loss or raising apport to report a presumed crash in some cases)
- list open files
lsof -i :<port_number>- Give details of which application/process is consuming the portlsof -nP +c 15 | grep LISTEN- Show list of all consumed ports in a machinelsof -h- Show list of all command line options
ipconfig getifaddr en1- on LANipconfig getifaddr en0- on WiFicurl ifconfig.me- public IP address