| querying other users by name | id (username) |
| executes the last command | !! |
| gives info on what command does | whatis file_name |
| gives info about type of file | file file_name |
| proposes commands | apropos |
| shows where command is installed | which command_name |
| makes directory | mkdir dir_name |
| creates file that doesnt exist or updates file's date | touch file_name |
| copies file to new file | cp old_file copy_of_file |
| rename file | mv old_name new_name |
| removes file | rm file_name |
| wildcard for multiple characters | * |
| removes directory | rm -r dir_name |
| removes empty directories | rmdir dir_name |
| escape character | \ |
| one level up | .. |
| home directory | ~ |
| reads from file
reads from file and enumerates lines
fills file with content/ creates file
concatenates files | cat file_name
cat -n file_name
cat >> file_name
cat file_1 file_2 |
| shows what is in the file | less- more advanced
more- less advanced
LOGICAL XD |
| new line | \ |
| changing prompt | PS1="new_prompt" |
| executes the last command | !! |
| clears current bash session history | history -c |
| clears history file, fills history file with emptiness | echo -n > .bash history |
| combines two commands | ;
cd ; pwd- changes to home dir and prints working dir |
| lists directories in root | ls / |
| lists directories in current working directory | ls
ls . |
| absolute path
relative path | /somepath
---------------
./somepath
somepath |
| preserve literal meaning of all enclosed characters
preserve literal meaning of all except: $ \ ` | ' '
" " |
| setting variable
acccessing variable | SOMEVAR ="sth"
echo $SOMEVAR
echo ${SOMEVAR} |
| displaying all variables | set |
| unsetting variable | unset SOMEVAR |
| printing environment | env |
| exporting variables to enviroment | export VARIABLE |
| selecting manual sections | man 1 kill
displays first section of man of kill command
don't specify parenthesis for functions |
| What is SSH | secure shell protocol enables two computers to commmunicate safely, it is encrypted
closing terminal results in killing all processes in current session |
| connecting via ssh | ssh [username@]hostname[.domainname] |
| What is GNU screen utility | Terminal multiplexer, by starting a screen session one can open many virtual terminals, processes runnning in screen will run even after disconnecting |
| makes a copy of everything that is printed on terminal and saves it into the ./typescript file | script-starts a script
exit-ends script
cat ./typescript- access to file |
| displays date | date |
| displays calendar of current month
displays calendar of whole year | cal
cal -y |
| displays system name
displays all the available information | uname
uname -a |
| hardware information | lscpu
lspci
lsusb |
| displays information on total and free memory | free
free -h -human readable version |
| displays the user and group IDs | id |
| querying other users by name | id username |
| user information lookup program | finger username |
| displays who is logged on the system | who |
| displays logged users and the commands they are running | w |
| sends a message to user
speccifying the terminal is necessary only if user is logged more than once
enables/disables incoming messages | write username [terminal]
mesg [y|n] |
