Common UNIX Commands. Unix. User Interfaces. Unix Commands Winter COMP 1270 Computer Usage II 9-1. Using UNIX. Unix has a command line interface

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1 Common UNIX Commands Using UNIX Unix Unix has a command line interface Unix commands must be typed Similar to the DOS operating system for PC s Compare to the Graphical User Interface (GUI) used by Windows, Mac and X-Windows Most commands to a GUI OS are given using point and click; no memorizing a long list of commands The command prompt indicates Unix is ready to accept your commands e.g. pollux 1% User Interfaces What s better, GUI or command line interfaces? Which is easier to use: For a beginner For an experienced user Which is more efficient/powerful? Are there other types of interfaces? Why do Windows and Mac OS X include command line interfaces? Why does Unix have a GUI interface? COMP 1270 Computer Usage II 9-1

2 Shells Your Unix commands are accepted and run by an interactive program called a shell There are several shells Korn Shell (ksh) - default shell for new users Bourne Shell (sh) - an early Unix shell C Shell (csh) - looks like the C programming language? Enhanced C Shell (tcsh) Use finger -m UMnetID to see the shell you are using (use your UMnetID) Unix Command Format command-name [-options] [arguments] Options are preceded by a dash and are used with Unix commands to modify their behaviour. Multiple options can be used; they are grouped together, preceded by a single dash Arguments are required with some commands; optional with others. They give the command some specific information about what they should operate on The [ ] are not typed; they are just there to show parts of the command that may or may not be present Command Options For example: ls (list contents of a directory) ls list files in current directory (no options) ls -l list files in current directory in long format ls -a list all files in current directory including invisible ones ls -al list all files in current directory including invisible ones in long format ls -F mark directories with a trailing / and files with "execute permission" with a trailing * ls option list: a A c C d f F g i l L q r R s t u 1 COMP 1270 Computer Usage II 9-2

3 Directory Shorthand Unix uses shorthand notation to make it easier to refer to certain directories. (dot) - current working directory.. (dotdot) - up one level (the parent directory) ~ (tilde) - your home directory ~user (tilde-user) - user s home directory Command Arguments For example: cd (change directory) cd move to your home directory (no argument) cd public_html move into public_html directory (located in the current directory) cd.. move up one level (the parent directory of the current directory) cd../graphics move up one level, then into the Graphics directory cd / move to the root directory cd ~ move to your home directory (same effect as the first example) cd ~umchan01 move to the home directory of user umchan01 Wildcard Characters Wildcards are placeholders you can use with command arguments? matches any single character * matches any number of characters (even none) e.g. c?t matches cat, cut, cot but not cart car* matches car, cart, carry, carnations Use wildcards in a command argument to specify multiple files COMP 1270 Computer Usage II 9-3

4 Wildcard examples For example: mv, cp and rm (move, copy and delete files) mv *.txt Documents move all files with the txt extension into the Documents directory mv UM*.gif../Images move image files with names beginning with UM into the Images directory in the parent directory cp ~/public_html/graphics/*.gif. copy image files in public_html/graphics to current working directory rm *.tmp delete all files with the extension tmp rm XYZ???.txt delete all text files beginning with XYZ and containing 3 more characters The mv and cp commands mv and cp have two uses: Move or copy files to a new location mv mypage.html A1 cp mypage.html A1 Move/copy mypage.html into A1 directory Move or copy files to a new name mv mypage.html index.html cp mypage.html index.html Move/copy mypage.html to index.html The mv command is used to rename files/directories More Unix Commands passwd Change password whoami who am I returns your userid not as silly as it sounds if you have several userids clear Clear the screen finger Find out details about other users good for finding userids of other users quota Find out how much disk space you have remaining COMP 1270 Computer Usage II 9-4

5 More Unix Commands du disk usage lists the size (in KB) of directories man Get a manual page on a command (help!) pwd Print working directory mkdir Make a directory rmdir Remove a directory File Protection in Unix Unix is typically a multi-user environment Your files are stored on a hard drive along with many other users files Normally we want to protect our files other users should not be able to change/copy/delete/run our files Sometimes we want other users to have access to our files group work, web sites, etc. File Protection in Unix Unix divides users into 3 categories users (i.e. the owners of files) groups (users can belong to named groups) others (all other users) Unix has 3 types of permissions that control what can be done with a file read permission write permission execute permission This gives 9 separate permissions that can be granted/denied for each file/directory COMP 1270 Computer Usage II 9-5

6 File permissions Use the long listing to view permissions each file is listed on its own line, e.g. castor 20% ls -l total 68 -rw-r--r-- 1 umchan01 student 8031 Jan 16 15:06 subject.txt -rw-r--r-- 1 umchan01 student 3321 Jan 16 15:11 UMhorz15.gif drwxr-xr-x 1 umchan01 student 512 Jan 16 15:11 public_html These groups of characters specify permissions a letter means permission is granted; a dash means it is denied File permissions There are actually 10 characters in the group used to specify permissions drwxr-xr-x Characters 8-10 show other user permissions Characters 5-7 show group permissions Characters 2-4 show user (owner) permissions Character 1 is d if the file is a directory (folder), or - if it is a plain file An example -rw-r--r-- 1 umchan student 8031 Jan 16 15:06 subject.txt -rw-r--r-- 1 umchan student 3321 Jan 16 15:11 UMhorz15.gif drwxr-xr-x 1 umchan student 512 Jan 16 15:11 public_html subject.txt (owned by user umchan) Has access rights - r w - r - - r - - The owner has the right to read and write to this file Members of the student group can read and copy it All other users may also read and copy it You are not given permission to modify it COMP 1270 Computer Usage II 9-6

7 Permissions and directories What do read, write and execute mean for a directory? Granting read permission gives the ability to list the contents of a directory Granting write permission gives the ability to change the contents of a directory Add/Delete/Move files Granting execute permission gives the ability to access the contents of a directory Important when we set up our web sites The chmod command chmod allows you to change access permissions to files and directories chmod requires 2 arguments which h permissions i are being changed which file/files are having their permissions changed wildcards come in handy here Changing Permissions To specify which permissions are being changed, we need (in order): 1) which user category or categories to change 2) whether permission is being granted or denied 3) which permission or permissions to change Letter codes specify category, permission user, group, other, all read, write, execute Use +/- to grant/deny permission COMP 1270 Computer Usage II 9-7

8 chmod Examples chmod o+r MyStuff.txt Grant to other users read permission For the file MyStuff.txt This command lets other users read (and copy) MyStuff.txt (provided you have granted access to the directory containing it) chmod u-w MyStuff.txt Deny to user (yourself) write permission For the file MyStuff.txt This command write-protects MyStuff.txt (you can always grant write permission to yourself again if you want to edit it) chmod Examples Can change access rights to your home directory as follows: chmod o+rx ~ Add read and execute access for other users For home directory only Recursive chmod Can apply chmod recursively - to a directory and all files/directories underneath it chmod -R o+r ~/public_html -R option means recursive Will give others read access to public_html and all files/directories contained inside, and everything inside those directories, and so on Try doing that with a GUI! COMP 1270 Computer Usage II 9-8

9 Web Publishing (the Unix way) We use sftp to transfer files to our Unix account Use Unix commands to manage the files Make directories if they re not there (e.g. mkdir public_html) To change to that directory, cd public_html Then if you do an ls -l, it will show you the files in the directory (and their permissions) Permissions Files are granted read permission to all so a web server can send a copy of the file chmod a+r file-name public_html directory (and all sub-directories) must have read and execute access So a web server can see and access files chmod -R a+rx public_html We also have to do something special to give others limited access to the main level of your account (so they can go down into public_html but not see your other files) One bit of Nastiness To do this, you must at some point type the following two commands: chmod g-l ~ (that's an L, lowercase) chmod a+x ~ These two commands allow the web server to get into your account in the first place They don't let it (or or other people) change your files Note that these permissions may have already been set by default, so first check that you are able to view your website with a web browser COMP 1270 Computer Usage II 9-9

10 Archive files Archive files collect a set of files and folders into a single file for backup purposes for easier portability Compression may also be applied to the files in the archive to reduce the size of the archive the original files are retrieved by uncompressing and extracting the archive file Archive files You will create an archive file when handing in web site design assignments It simplifies the hand in procedure (only 1 file) It preserves the structure of your web site You use an archiving utility to create an archive We will look at Power Archiver, which is available in the labs Archiving utilities Power Archiver is installed in the Open Area Computers It is available from Software Express for home use This utility is integrated directly into Windows Explorer The Explorer bar (left pane) is set to display folders (View Explorer Bar Folders) You create a compressed archive by rightclicking on a folder in the Explorer Bar COMP 1270 Computer Usage II 9-10

11 An archiving example Stew Dent has created a web site It is contained in the folder A03_umdent It contains a subfolder called images Stew right-clicks A03_umdent Compress to A03_umdent.zip The archive A03_umdent.zip is created The archive file can be renamed if needed With OS X on a Macintosh Select a folder From the File menu, click on Compress folder name COMP 1270 Computer Usage II 9-11