Using Linux
Linux (pronounced lee-nucks) is the name given to a family of Unix-like operating systems. The Linux kernel was originally developed by Linus Torvalds in 1991. Red Hat Enterprise Linux is the operating system on Super Computing Wales which was originally developed by Red Hat Incorporated in 1993. Linux was originally developed as a free Unix-like operating system for Intel x86 based personal computers. It has since been ported to more computer hardware platforms than any other operating system. It is a leading operating system on servers and other big iron systems such as mainframes and supercomputers.
Command Prompt Basics
| Command | Description |
|---|---|
| man man | displays manual information on the manual command |
| man <command> | displays manual information on <command> |
| clear | clears the screen |
| exit | exits the command interpreter |
Manipulating Directories
| Command | Description |
|---|---|
| cd .. | change to the parent directory |
| cd <directory> | change to directory <directory> |
| mkdir <directory> | create directory <directory> |
| rmdir <directory> | remove directory <directory> |
Listing Files
| Command | Description |
|---|---|
| ls | display list of files and sub directories in standard format < name > excluding hidden files |
| ls -a | display list of files and sub directories in standard format < name > including hidden files |
| ls -l | display list of files and sub directories in long format < permissions owner group size date time name > |
| ls -lh | display list of files and sub directories in long format < permissions owner group size date time name > with human readable size |
| ls -lt | display list of files and sub directories in long format < permissions owner group size date time name > sorted by time |
| ls -lr | display list of files and sub directories in long format < permissions owner group size date time name > in reverse order |
| ls -ltrh | display list of files and sub directories in long format < permissions owner group size date time name > sorted by time, in reverse order, with human readable size |
Moving Files
| Command | Description |
|---|---|
| mv <source> <dest> | move file <source> to file <dest> |
| mv -i <source> <dest> | move file <source> to file <dest> prompt before overwriting if it exists |
| mv -f <source> <dest> | move file <source> to file <dest> overwrite <dest> if it exists |
Removing Files
| Command | Description |
|---|---|
| rm <file> | remove file <file> |
| rm -i <file> | remove file <file> prompt before removing |
| rm -r <directory> | remove directory <directory> |
| rm –rf <directory> | remove all sub directories and files |
Copying Files
| Command | Description |
|---|---|
| cp <source> <dest> | copy file <source> to file <dest> |
| cp -i <source> <dest> | copy file <source> to file <dest> prompt before overwriting <dest> if it exists |
| cp -r <source> <dest> | copy directory <source> to directory <dest> copy all sub directories and files |
Comparing Files
| Command | Description |
|---|---|
| diff <file1> <file2> | display differences between <file1> and <file2> |
| fgrep “string” <file> | find “string” in <file> |
| sort <file> | sorts each line in <file> alphanumerically |
Other Commands
| Command | Description |
|---|---|
| who | show who is logged on |
| top | show which tasks are running |
| watch <command> | run <command> repeatedly |
| history | show which commands you ran |
| date | display the date and time |
| time <command> | displays the time taken to run <command> |
| more <file> | displays a file on screen |
| cat <file> <files> | concatenate file or files and print on screen |
| head <file> | print top of file on screen |
| tail <file> | print bottom of file on screen |
| uniq <file> | omit repeated lines |
Command Modifiers
Wildcards allow you to specify multiple items to operate on
ls *.txt rm *.txt
Redirection allows you to direct the output of one command to a file
sort unsorted.txt > sorted.txt
Filters are external commands that change data in some manner
fgrep “string” <file>
Pipes let you direct the output of one command as input to another
ls | fgrep "txt"