Session 2: More File Management and Text Editing

Transcription

1 1 of 11 1st Year Computing for Engineering Session 2: More File Management and Text Editing Michaelmas Term 1999 Lab Organizer: Prof D W Murray In the first session you became familiar with Openwindows, and the organization of a filestore into directories and files. In this session, you will gain more practice with Unix commands, especially ones that move, copy and delete files in the filestore. You will then practice using a text editor. You will find it useful to keep a running sketch of the filestore when running through the notes on copy, remove, rename. This should be a sketch and not an engineering drawing, but nonetheless your logbook, not the back of an envelope, is the natural place for such work. You are (probably) working in pairs. As last time, make sure both of you get a fair go at the keyboard. There is no need though to logout and login half way through as in Session 1. Upfront apology! Moving files around is definitely NOT the most interesting thing in the world, but it is important that you become confident and competent, so that the Suns become useful tools for you later on. Bear with it please. Summary of what you have to do this session More Unix Spend about 40 minutes working through. There is no need to record this. Exercise 2 Spend about 40 minutes on this. Record your work in your logbook. Text Editing Spend about 35 minutes on this. There is no need to record this. Document conventions this typeface indicates something the machine should present,

2 2 of 11 this typeface indicates something you should type. In places, only the short prompt % will be given. 1. Getting Started Partner 1 log in and start up Openwindows. Change directory into session2, then make four directories, called spring, summer, autumn and winter. booth42.ecs:/blah/u98xxx% cd session2 booth42.ecs:/blah/u98xxx/session2% mkdir spring summer autumn winter Now generate the following files using redirection and then cat. (Don't worry about typing the poems completely or accurately!) Type % cal > sep % cal > oct % cal > nov % cal > dec % cat > poem1 What is this thing called enthalpy, or H, or U plus P times V? I've not a clue --- but joy! I see Its all explained in HLT. ctrl-d (Press ctrl key and the d key) 2. Deleting, Copying and Moving Three of the most commonly used commands are those to copy, delete and move (that is, rename) files. Type `ls -F' to remind you of the directory contents. You should have autumn/ nov poem1 spring/ winter/ dec oct sep summer/ though some of the files may have * by them -- no need to worry about this. As suggested at the start, make a sketch of this to help keep track. Now try copying the file poem1 to the file newpoem: % cp poem1 newpoem Remember these files have the same contents, but are distinct. Try ls -l to check that they are the same size, but have different times of creation. There is incidentally a command that looks for differences between contents of files. Type % diff poem1 newpoem % diff poem1 dec and see what happens.

3 3 of 11 If you delete ``poem1'', the ``newpoem'' file still exists. Try it. % rm poem1 Note that it asks for confirmation. Now rename the file newpoem using the following % mv newpoem poem2 Now `ls -l ' indicates that there is no file called newpoem, but there is one called poem2. Same contents, different name. Each disk holds a table of contents as well as files. When you copy a file, a new file is created, and a new entry in the table. When you move or rename a file, only the name in the table of contents is changed. 2.1 Copying files into different directories All the examples above took place in the session2 directory. Now you are to explore copying etc between directories. For this exercise you will make calendars for the various months, and then play with them. Remember that it will help you if you keep a running sketch. Now let us copy sep to the autumn directory. Relative to where we are now the new file name is autumn/sep, so: % cp sep autumn/sep The cp and mv commands can be used in a variety of ways however. So far we have used cp filename1 filename2, but copy can also perform cp filename directoryname. The program detects that the last argument is a directory and performs cp ~filename ~directoryname/filename That is, the file is copied into the new directory with the same name. Type % cp oct ~autumn % cd autumn % ls % cd.. to check that this works. Move works in just the same way: % mv nov autumn Now make a deliberate mistake: % mv dec autumn To recover, ``cd'' into autumn, and check dec is there: % cd autumn % ls You wish to ``mv'' dec into winter. But you cannot just say % mv dec winter Why not?

4 4 of 11 The reason is that winter is not a subdirectory of autumn --- it is a subdirectory of session2 which lies above autumn. In fact if you typed the above, because winter is not a valid subdirectory of autumn, Unix would think that winter must be a filename, and it would rename the file to winter. Try it now, then repair the damage immediately! % mv dec winter (oops) % ls (check what has happened) % mv winter dec (repair) Now back to what we were trying to do. Directory winter is a subdirectory of the directory above us. The directory above has the shorthand dot-dot "..", so the following should work. Type: % mv dec../winter There are actually many ways of specifying the target directory. Let's generate a new file in the wrong place now by typing % cal > jan Winter is a subdirectory of session2; but session2 is a subdirectory of your home directory; so that you could move file jan to directory winter by typing % mv jan ~/session2/winter Now make another mistake by typing fab: % cal > fab This time to move we need to change the file name when we move, as in EITHER OR % mv fab../winter/feb % mv fab ~/session2/winter/feb Now change directory into winter to check that dec, jan and feb are there. If you are about to type cd winter stop right now, and think!! 3. Copying, moving and deleting directories and their contents Suppose that there are two subdirectories in your current directory. Typing % mv directory1 directory2 will move directory1 so that it becomes a subdirectory of directory2. You must be careful of course to ensure that the directory names are valid given the directory in which you are sitting. For example sitting in autumn and typing % mv summer autumn does not make sense, but it would when sitting in session2. Also when sitting in autumn % mv../summer autumn

5 5 of 11 does NOT make sense. The directory autumn is not a subdirectory of autumn. Several ways of doing the same thing while sitting in autumn are % mv../summer ~/session2/autumn % mv../summer../autumn % mv../summer. Note: just as dot-dot ``..'' stands for the parent directory, the dot ``.'' stands for the current working directory. Another example of using the dot. is when you wish to copy a distant file to your current working directory: Eg % cp ~/datefile. Copy directories and their contents is a little more tricky. Suppose summer contained jun,jul,aug. Sitting in autumn we would do a recursive copy: % cp -r../summer. This says to copy the summer, and the entire tree branching from summer, to autumn. If, however, you just wanted to copy the files from summer: % cp../summer/*. would do the trick. If the copy program came across a directory name in summer, it would tell you that the directory was not a regular file, and that it was not copying. 4. Protecting your files Change directory to your home directory and type ls -l. You will see lines similar to something like: drwx--x--x 2 u99xxx -rw u99xxx 512 Oct 19 17:32 session2 29 Oct 19 17:32 datefile The zeroth column in rwxrwxrwx <--- Read Write execute uuugggooo <--- User Group Others indicates whether the file is a directory (d), a standard file (-) or something more esoteric. Columns 1-9 indicate the read, write, and execute permissions for the files and directories. The ``user'' is you, ie u99xxx, the ``group'' includes all u96'ers, and ``others'' embraces all other people. Permissions can be changed using chmod. For example, to give others permission to read file datefile, and remove execute permission from others and group on session1: booth42.ecs:/blah/u98xxx% chmod o+r datefile booth42.ecs:/blah/u98xxx% chmod og-x session1 One way of giving yourself blanket protection from others is to type

6 6 of 11 booth42.ecs:/blah/u98xxx% chmod og-rwx ~ This prevents anyone from doing anything to your home directory and any directory beneath your home --- ie your entire filestore. Play with changing the permissions on datefile, and each time, do ls -l datefile to check that what you think should happen has happened. Then type booth42.ecs:/blah/u98xxx% chmod u-x session2 booth42.ecs:/blah/u98xxx% cd session2 Surprised? Yes, you need execute permission to cd into a directory. This facility prevents snooping of your filestore by others. They can't read, write and can't see what is there to read either! You should restore your permission to cd into your own session2 directory. EXERCISE 2 You must record your results for the exercise in your logbook. Preamble Are you in your home directory? If not, get there. From your home directory type booth42.ecs:/blah/u98xxx% /mclab/demo/yr1/script2 [return] This shell program makes a new directory called exercise2 with subdirectories in the tree shown in Figure 2.1.

7 7 of 11 Fig 2.1: The filestore created by script2 The tasks Sort out the mess! cd into directory ``others'' and move any files and directories not associated with the seasons and months into it. (By convention Spring runs from Mar-May, Summer from Jun-Aug and Autumn from Sep-Nov.) sort out the summer directory so that it is sitting in exercise2, not in autumn. Rename jeb to feb, and move files to their proper seasons. change the permissions on the files in spring, so that all can write to them. change directory to exercise2, and in one command copy all the files in ``others'' into exercise2. delete the directory ``others'' and its contents. call a demonstrator to check your work, then cd into your home directory, and delete recursively exercise2, and all that therein is.

8 8 of Text Editting 5.1 Basic use of TextEdit Earlier in this session you used the cat command to create a text file containing a poem. This is not very convenient, because once you press return after a line, you cannot correct it at all. Obviously, much better to use a text editor. When you start up Openwindows, a TextEdit window appears at the top right of the screen. The window appears similar to that of a cmdtool window, but notice that there is no prompt --- typing into a Text Editor does not talk to Unix. Follow these points to see how the editor works. Type the following into the text editor, adding in the mishtakes and bludners. That is, type the following text exactly as you see it Delete this as a block Delete this as a block Delete this as a block X To save this, use the Menu mouse button (RIGHT BUTTON) on the File menu selector at the top. Now choose Store as a New File. A panel appears on the screen asking for a file name. But wait! The Directory line indicates that Textedit is ``sitting in'' /whatever/u99xxx but you want the file to go into the session2 directory. To change the current directory, simply click the Select (LEFT) button at the end of u99xxx, and add /session2, so that Textedit is ``sitting in'' /whatever/u99xxx/session2. Now select the File line, and type the file name --- some.dat --- then press the ``Store as a New File'' button. The panel vanishes, and the file is saved. Notice that the textedit copy of the file remains in the window, and one could continue editing. Indeed, it is good practice when typing a long document to save every five minutes or so. Having saved the file, move the pointer to the cmdtool, and cd into session3. You should see the file --- type it out using cat some.dat Now pretend you have just noticed the errors. You need to edit the file! There are two common operations in editing:

9 9 of Point and click to a position in the text, then type or delete text/ This is useful when you have put in or missed out a few characters or words. Move the mouse to the point in the text and click. The caret indicates the current typing point. Cut and paste This is where you select a region and cut it out, and then possibly move to a new position and reinsert it. Fix the mistakes in your text using both these methods. For example, you could 1. delete the "Delete this etc" lines by selecting and cutting 2. replace the "X" with "0" using point and click, and so on. Once finished, save the edited file. Point the mouse up at the File menu and choose ``Save Current File''. The editor saves the file using the name you gave previously. It also moves the previous version to some.dat\% as a backup. Go back to the cmdtool and % ls -l % cat some.dat\% % cat some.dat to check that the contents of the files are as you expect. Now practice reloading a file into the editor after editing some other file. 1. Press empty document in the textexitor. 2. Load the file ``dec'' to the textedit window, replacing the some.dat file completely. 3. Make a few changes and then save it. 4. Now get some.dat back into the texteditor, add and extra data line and save it. 5.2 Other Menu options in TextEdit Read the following and if you have time check out what it tells you by selecting the various options. The other options on the File Menu are "Load file", "Include File" and "Empty Document" --- all are self explanatory. The other menus under "Edit", "Find" and "View". are also quite obvious, and here we only give the briefest remarks. [Edit] If you select a point in the text using the Select (LEFT) button and drag the mouse, you will highlight a block of text. When you use Cut, the block is removed and placed in the Cut-Buffer. You can then move the cursor to another place in the document and use Paste to insert at that point. Copy also puts the text in the Cut-Buffer, but leaves the original where it is. Undo is also useful: it has two options, one to undo the last edit, one to restore the text to its condition when you loaded it. [Find] The Find menu has a variety of ways of searching for specific bits of text and replacing bits of text. [View] Amongst other things, this menu enables one to go a specific line in a document. This is often useful when programming: the compiler might indicate an error in line 576, say in the cmdtool window.

10 10 of 11 If you highlight the number by dragging mouse with the select button down (yes, from the cmdtool window) then choose Select Line at Number, the text caret will jump there immediately. 6. Printing Text files created by an editor or program can be printed out using the lp command. There are both dot matrix and laser printers available to you: they reside in ``the small room'' on Level 6. As you face the walls with the doors, go out of the right hand door, turn right down the stairs and the room is straight ahead. A default printer will have been set up for you. Type % lpstat -s scheduler is running system default destination: ew system for ep: heath.ecs system for ew: robinson.ecs To print on the default printer, (here ew, a dot matrix) type % lp yourfilename but to print on the laser printer called ep % lp -d ep yourfilename In each case the printer job is put in the printer queue, and the machine will return a ``request id'' such as ``ew-10'' Typing % lpstat will show you the jobs on the queue You might see something like ew-5 bert 720 Oct 12 17:34 on booth31.ecs ew-10 u99xxx 1261 Oct 12 17:36 on booth41.ecs If you want to withdraw your job from a queue --- either because you have sent the wrong file or there are 37 huge jobs ahead of you and you don't have time to wait --- try % cancel ew-10 There are many options that you can apply to lp. Perhaps one of the most useful is % lp -w yourfilename which will write a message to the screen when the printing is finished. 6.1 Print sparingly! There are quotas You should print sparingly. The window environment and text previewers and interactive debuggers make it an easy job to check for typographical or programming errors on the screen. To deter you, there are limits on the amount of paper and disk store you are allow to fill up. To obtain information about your quota and usage, type % quota -v

11 11 of Clearing up and Logging Out Once the session has been signed off, you may remove all the files in the directories session2 and exercise2, and the directories themselves using % cd ~ % rm -r session2 % rm -r exercise2 Now Log Out! First Exit Openwindows Then Logout from the console Don't forget this! Summary of sessions 1 and 2 After these sessions, you should: Be able to log on, to open and manipulate windows, and to log out. Understand the structure of a file system, and the notions of home directory, current working directory, parent directory, and subdirectory. You should be able to change your current working directory. Be able to remove, copy and move files around the filesystem. Be able to generate text files, store and re-edit files using the text editor. If you don't yet feel comfortable, you may need extra practice. Remember that the Solarium is available to you outside of laboratory sessions. Lab devised by: David Murray Lab Organizer: David Murray Last changed June 15th, 1999