diff --git a/README.md b/README.md index b241791..d9fbc85 100644 --- a/README.md +++ b/README.md @@ -1,3 +1,198 @@ -# Important-Linux-commands +## Important-Linux-commands + +The commands which make life in cyberspace easier. + +In the shell, you have to imagine the jumps. Because the computer will only be +projecting code in your mind from your mind. + +You are a specific point on some system, when you are in the shell. +you can see what is in the directory you are with the command + +# ls + +this command also can display other useful information. Of what is inside the directory +you are in. + +# cd + +The most important one. +Instead to click, you change directories via command. +that makes it possible to jump from one point to the other, especially with autocompletion. + + +# man + +In general you can get the manual entries for each of the programs described here and much more. + +Just type + + man cd + +or type + man ls + +and you will get the manual opened historically with nano or less.. not sure, both good old editors. + +# cp + +copy files from one place to another. (relatively from you) + + cp /dirA/file1.py /dirB/file1.py + +when there is already file1.py in the destination directory, it gets overwritten. + + + +# Concept of piping with > + +in the shell you have standard input and standard output. +Nothing more. +to pipe the standard output from one program into a file, you write it like this: + + ls > file.txt + +When you write like that, youll overwrite everything in the file with the output. + +If you want to append to a file what a program has as standard output, +you can use >> instead. Writing it like this: + + ls >> file.txt + +This both is piping. There is another very important aspect of piping described later. + +# alias + + +give your complicated commands easy remember commands. +Or build the own language of your shell. + + alias cls=clear + +This sets up an alias called cls. It will be another name for clear. When you type cls, it will clear the screen just as though you had typed clear. + +On my Arch Linux, I can write these aliases in my bashrc config file. I need to issue the command + + source bash_profile + +to get the configuration loaded. On other linux there will be an analogon. + + + +# cat + +print out what you have in front of you on the standard output. + +also print several together + +for instance: + + cat doc1.txt doc2.txt > doc1ANDdoc2.txt + + +# chown + +On linux everything are only directories and (txt)files. +All these objects have an owner, or also multiple ones. + + sudo chown -R root /ole/ola/kp.txt + +gives root the ownership of kp.txt + +# chmod + +Every owner then has file permissions. That means he can read write or x (do) something. +he can do all of them or some of them or none of them. Thats defined in codes, 777 gives them all and 660 doesnt completely. + + sudo chmod 777 ole/oi/file.txt + +bzw + + sudo chmod 660 ole/oi/file.txt + + + Just look it up what people say regarding permissions and certain directories. + +# history + +this lists all the commands of the shell you are in, that you have typed in lastly. + +# grep + + +if you have some bigger output of some of the former commands for example. Or whatever big output. then use grep to filter out the lines that have a certain word in it. +GRAB it. + +# piping with | + +here comes into account the piping with |. + +Directly combining it with the history command is pretty effective.. + + history | grep "whatsoevercommandIalreadyfiguredoutbutreallydontwanttosearchoutagain" + +here the output of history gets piped into the program grep. +as the output of history gives one command per line, grep will filter out exactly the command in which the pattern "whatsoever" occur. + + +# getting some INFO about the system + + +# df + +prints you out disc usage of your hardware + + df -h + +does it in humanreadable + + +# du + +prints out the size of files around you + + du -h -d 2 + +prints in human readable with depth 2, that means in the directories and in their subdirectories. + + +# lsblk + +prints you out all the hardware devices with memory + + +# htop respectively top + +gives you a terminal graphics programm interface to see all running processes + + +# tail -f + +with tail or also head, you can print out the last or the first lines of a file + +When you use tail -f, you get a stream of the documents last lines. + +Thats perfect for some log files that get written. + +# journalctl -f + +this gives you a stream of the kernel messages, which are pretty a lot about a lot of different topics of the programs on your machine. + +The kernel is the ground software, running the hardware of the proper materia device. +Its mostly in C. +C is like the base of all languages. (if its not assembly) + +# uname (-a or -r or other) + +gives you general infos about system, OS, and stuff + +# systemctl + +some people do not like systemctl. +I personally have parts of my structures that are managed by this software. +with + + sudo systemctl status nginx.service + +I ask systemctl to give me the status of the nginx daemon, running in the background of my (and actually all of my machines there is running one nginx daemon) machine. + -The commands which make life in cyberspace easier \ No newline at end of file