Unix Command Line help
Commands
Display the manual for command (man <command>)
Navigation (cd <path>)
Display directory Contents (ls -lh <path>)
Show current directory path (pwd)
Clear the terminal screen (clear)
Quit the command line session (exit)
Create a virtual terminal (screen -S <name>)
Check what processes are running (ps fwux)
Terminate a process (kill -HUP <pid> or kill -9 <pid>)
List top running processes (top)
Make a command share system resources fairly (nice <command>)
Make an existing process share system resources fairly (renice +<0 to 20> <pid>)
Display file contents (cat <file>)
Display file contents one page at a time (less <file>)
Search for text strings in a file (grep -i <pattern> <file>)
Display the manual for a command
| command: man <command> description: * shows the manual page for <command>. This is a great way to learn of the other options and features a command has and also related commands * adding ‘-k’ searches through all manuals for occurances of the text you enter as <command> |
| command: cd <path> description: * change directory to <path> * used without <path> will change to your home directory |
| command: ls -lh <path> description: * shows the contents of directory at <path> * ‘l’ shows extra details such as permissions, file size and date * ‘h’ shows the file size in human readable form (in GB, MB, etc) * used without <path> will show the curent directory |
| command: pwd description: * prints out the path of the current directory you are in |
| command: clear description: * clears the text from the termal (pressing ctrl-L does the same) |
| command: exit description: * quits the shell session, which may close the terminal window or will disconnect from the remote server if you connected via SSH |
| command: screen -S <name> description: * creates a virtual terminal session that you can reconnect to later * (text based) programs can continue to run in the virtual terminal even if you disconnect from the server * <name> is a unique name to help you identify and reconnect to your screen (you can create multiple screens) * use screen -rd <name> to reconnect to your screen session (‘r’ is reattach and ‘d’ is detach if still connected elsewhere) * colour text sometimes does not show up, one workaround is to let screen start the program, such as: screen -S filemanager mc (starts midnight commander and calls the screen ‘filemanager’) |
Check what processes are running
| command: ps fwux description: * shows your current processes running on the server * ‘f’ shows a process tree so that you can tell easily which processes are the parents and child processes * ‘w’ wraps the text output so that you can see the process name and command line options that were specified * ‘u’ shows username owning the process and some stats * ‘x’ list all processes owned by you * adding ‘a’ will show all processes running on the system |
| command: kill -HUP <pid> or kill -9 <pid> description: * Use this command to kill a process that you cannot quit normally. <pid> can be found using the ps command. * ‘HUP’ sends the hang up signal, the process should try to quit normally * ‘9’ sends a ‘-KILL’ signal (‘9’ is faster to type), which will forcefully end a process. This is useful if you cannot end a program even with the ‘-HUP’ signal. |
| command: top description: * shows what processes are using the most resources. use ‘q’ to quit; ‘u’ to show a specific username |
Make a command share system resources fairly
| command: nice <command> description: * runs a command with adjusted scheduling so that it does shares resources with other process more fairly |
Make an existing process share system resources fairly
| command: renice +<0 to 20> <pid> description: * allows you to ‘nice’ a process that is already running (make it ‘nicer’) |
| command: cat <file> description: * displays the entire file contents on the screen |
Display file contents one page at a time
| command: less <file> description: * shows the contents of a (text) file one page at a time |
Search for text strings in a file
| command: grep -i <pattern> <file> description: * search through <file> for <pattern>, matched lines will be displayed * ‘i’ means ignore case (match upper or lower characters) |