| Changing your password: | |
| passwd | Do this ASAP! |
| Cruising the Shell: |
|
| cd | moves you to your home directory |
| cd directoryname | moves you to that directory named directoryname |
| cd .. | moves you to the parent of the current directory |
| pwd | displays the path of the working (current) directory |
| ls | displays a listing of files in the current directory |
| ls -a | displays all files, including hidden files such as .profile and .login * |
| * Attempting to modify any of these special files can wreak havoc on your environment if you don't know what you are doing! | |
| ls -l | displays more information on each file, including permissions |
| r command | r will search command buffer as you type and will substitute a match.. can save time when executing same command many times |
| clear | clears the screen |
| script filename | starts a log file of your Unix session and writes it to filename. end the script by typing control-d |
| man commandname | displays documentation for that command, use space bar to move f rom page to page |
| man -k word | displays all commands where word is a keyword |
| help commandname | similar to man, less technical |
| exit | End the Unix session. logout may also work |
| Working with Files and Directories: |
|
| pwd |
displays your present directory |
| mkdir directoryname | creates a subdirectory off of the current directory named directoryname |
| rmdir directoryname | removes the directory named directoryname from the current directory (the directory being removed must be empty first) |
| cp filel file2 | copies filel to file2 |
| cp -i filel file2 | copies filel to file2. prompts for confirmation if file2 already exists |
| cp fname dname | copies file fname into directory dname |
| mv fname dname |
moves file fname into directory dname |
| mv fname1 fname2 |
renames file fname1 as fname2 |
| rm filename | deletes filename |
| rm - i filename | prompts for y or n before deleting file |
| lpr –ppname fname | prints the file fname to the printer pname |
| lpq -ppname | shows the printer queue (including job numbers) for pname |
| lprm – ppname jobnumber | removes job number jobnumber from pname's job queue |
| more filename | shows the contents of filename, one page at time, use the spacebar to see the next page, q to quit.... |
| ex: ls –l | more | also can be used as a "pipe" to control system output |
| page filename | a little more versatile than more, press ‘-' to go back a page or type a number to go to that page |
| cat filename | will display contents of filename |
| cat file1 file2 > file3 | concatenates file1 and file2 into file3 |
| Permissions: |
|
| Access to files and directories is controlled through
the granting and revoking of permissions. You must have permission to read
(r), write (w) or execute (x) a file (even your own!), and similarly you
must have permission to view filenames (r), add or delete files (w), or search
through (x) a directory. The owner (creator) of a file or directory can assign
permissions to himself, to all members of a specific group, or to everyone.
You can view permissions for files by performing a long listing (ls -l).
The permissions will look something like this: _rwxrw_r_ _ The first space is only there to differentiate different types of objects (blank for file, d for directory, l for a link). The following three characters (r w x) are the permissions for the owner aka user (u) of the file. In this case the user has read (r), write (w) and execute (x) permissions. The next three characters (r _ _) are the permissions for other members of the owner's group (g). They have permission to read (r) and write (w). The last three characters are the permissions for everyone else (o). They only have read (r) permission. |
|
| chmod u=rwx,g=rw,o=r filename | Sets the above permissions for filename |
| chmod o+w filename | Grants write privileges for filename to others |
| Octal notation: Each group of 3 permissions
is assigned a 3 digit binary value: 22 21 20
r w x for example: _ _ _= 0 = no permissions _ _ 1 = 1 = execute permission only _ 1 _ = 2 = write permission only 1 _ _ = 4 = read permission only 1 _ 1 = 1 + 4 = 5 = execute and read permission only 1 1 1 = 4 + 2 + 1 = 7 = read, write and execute permissions. |
|
| chmod 777 filename | Grants all permissions to everyone for filename, using octal notation |
| In general, your directory permissions should be set to: r w x _ _ _ _ _ _ (700). Permissions to your no non-executable files should be set to r w _ _ _ _ _ _ _ (600), and permissions for executable files should be set to r w x _ _ _ _ _ _ (700). This will protect your work from being copied or vandalized by others. |
|
| Other People: |
|
| finger username |
Will display when username was last on, if
they have mail, and their profile. |
| talk username
|
Displays if username is on, if so allows you
to write back and forth in real time. |
| Special Characters: |
|
| The following characters have special meaning in Unix and should not be used in filenames: & ; | * ? ' " [ ] ( ) $ < > { } ^ # \ / | |
| OOOPS: |
|
| If you need to stop a currently executing command (process), | |
| kill anumber | kills the process with the PID number anumber. |
| ki1l -9 anumber | kills the process and all associated processes. |
| ps -u username | displays all current processes (and their PID's) belonging to username |
| ps -lu username | displays more info about username's current processes |
| control-u | kills the current command line (before you hit enter) |
| control-c | may interrupt the current process |
| control-d | exits some processes (such as script) |
| control-z | sends a process to the background |
| control-h, backspace, delete | erase a character |
| Being a VIP (a VI (editor) Person) |
|
| vi | One of the most powerful text editors in the UNIX environment. Some of the most common VI editing commands |
| Other Editors: |
|
| pico | Easy to use, multiline editing capability. Editing commands are a subset of the emacs commands |
| emacs | Very powerful development environment, including a text editor. |
| Compilers: |
|
| Gnu Compiler: | |
| g++ filename.cpp | Compile filename.cpp and create an executable file, a.out |
| g++ -c filename.cpp | Compile only (create object file) |
| g++ -Wall filename.cpp | Compile filename.cpp and list all warnings |
| g++ filename.cpp -o newname | Compile filename.cpp and create executable newname |
| HP Compiler: Check the online manual (man CC) |
|