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Annotation of 43BSDReno/share/doc/usd/12.edtut/e2, revision 1.1

1.1     ! root        1: .\"    @(#)e2  6.1 (Berkeley) 5/22/86
        !             2: .\"
        !             3: .SH
        !             4: Writing text out as a file \- the Write command ``w''
        !             5: .PP
        !             6: It's likely that you'll want to save your text for later use.
        !             7: To write out the contents of the buffer onto a file,
        !             8: use the
        !             9: .ul
        !            10: write
        !            11: command
        !            12: .P1
        !            13: w
        !            14: .P2
        !            15: followed by the filename you want to write on.
        !            16: This will copy the buffer's contents
        !            17: onto the specified file
        !            18: (destroying any previous information on the file).
        !            19: To save
        !            20: the text on a file named
        !            21: .UL junk ,
        !            22: for example, type
        !            23: .P1
        !            24: w junk
        !            25: .P2
        !            26: Leave a space between
        !            27: .UL w
        !            28: and the file name.
        !            29: .ul
        !            30: Ed
        !            31: will respond by printing
        !            32: the number of characters it wrote out.
        !            33: In this case,
        !            34: .ul
        !            35: ed
        !            36: would respond with
        !            37: .P1
        !            38: 68
        !            39: .P2
        !            40: (Remember that blanks and the return character at the end of each
        !            41: line are included in the character count.)
        !            42: Writing a file just makes a copy of the text \- the
        !            43: buffer's contents are not disturbed, so you can go on adding
        !            44: lines to it.
        !            45: This is an important point.
        !            46: .ul
        !            47: Ed
        !            48: at all times works on a copy
        !            49: of a file, not the file itself.
        !            50: No change in the contents
        !            51: of a file takes place until you give a
        !            52: .UL w
        !            53: command.
        !            54: (Writing out the text onto a file from time to time as it is being
        !            55: created is a good idea, since if the system crashes or if you make some horrible mistake, you will lose
        !            56: all the text in the buffer but any text that was written onto
        !            57: a file is relatively safe.)
        !            58: .SH
        !            59: Leaving ed \- the Quit command ``q''
        !            60: .PP
        !            61: To terminate a session with
        !            62: .IT ed ,
        !            63: save the text you're working on
        !            64: by writing it onto a file using the
        !            65: .UL w
        !            66: command,
        !            67: and then type the command
        !            68: .P1
        !            69: q
        !            70: .P2
        !            71: which
        !            72: stands for
        !            73: .IT quit .
        !            74: The system will respond with
        !            75: the prompt character
        !            76: .UL $ "" (
        !            77: or
        !            78: .UL % ).
        !            79: At
        !            80: this point your buffer vanishes, with all its text,
        !            81: which is why you want to write it out before quitting.\(dg
        !            82: .FS
        !            83: \(dg Actually,
        !            84: .IT ed
        !            85: will print 
        !            86: .UL ?
        !            87: if you try to quit without writing.
        !            88: At that point, write if you want;
        !            89: if not, another
        !            90: .UL q
        !            91: will get you out regardless.
        !            92: .FE
        !            93: .SH
        !            94: Exercise 1:
        !            95: .PP
        !            96: Enter
        !            97: .ul
        !            98: ed
        !            99: and
        !           100: create some text using
        !           101: .P1
        !           102: a
        !           103: \&. . . text . . .
        !           104: \&\fB.\fR
        !           105: .P2
        !           106: Write it out using
        !           107: .UL w .
        !           108: Then leave
        !           109: .ul
        !           110: ed
        !           111: with the
        !           112: .UL q
        !           113: command, and print the file,
        !           114: to see that everything worked.
        !           115: (To print a file, say
        !           116: .P1
        !           117: pr filename
        !           118: .P2
        !           119: or
        !           120: .P1
        !           121: cat filename
        !           122: .P2
        !           123: in response to
        !           124: the prompt character.
        !           125: Try both.)
        !           126: .SH
        !           127: Reading text from a file \- the Edit command ``e''
        !           128: .PP
        !           129: A common way to get text into the buffer is to read it
        !           130: from a file in the file system.
        !           131: This is what you do to edit text
        !           132: that you saved with the 
        !           133: .UL w
        !           134: command in a previous session.
        !           135: The
        !           136: .ul
        !           137: edit
        !           138: command
        !           139: .UL e
        !           140: fetches the entire contents of a file into the buffer.
        !           141: So if you had saved the three lines
        !           142: ``Now is the time'', etc.,
        !           143: with a
        !           144: .UL w
        !           145: command in an earlier session,
        !           146: the 
        !           147: .ul
        !           148: ed
        !           149: command
        !           150: .P1
        !           151: e junk
        !           152: .P2
        !           153: would fetch the entire contents of the file
        !           154: .UL junk
        !           155: into the buffer, and respond
        !           156: .P1
        !           157: 68
        !           158: .P2
        !           159: which is the number of characters in
        !           160: .UL junk .
        !           161: .ul
        !           162: If anything was already in the buffer, it is deleted first.
        !           163: .PP
        !           164: If you use the
        !           165: .UL e
        !           166: command to read a file into the buffer,
        !           167: then you need not use a file name after a subsequent
        !           168: .UL w
        !           169: command;
        !           170: .ul
        !           171: ed
        !           172: remembers the last file name used in an
        !           173: .UL e
        !           174: command,
        !           175: and
        !           176: .UL w
        !           177: will write on this file.
        !           178: Thus a good way to operate is
        !           179: .P1
        !           180: ed
        !           181: e file
        !           182: [editing session]
        !           183: w
        !           184: q
        !           185: .P2
        !           186: This way, you can simply say
        !           187: .UL w
        !           188: from time to time,
        !           189: and be secure in the knowledge that
        !           190: if you got the file name right at the beginning,
        !           191: you are writing into the proper file each time.
        !           192: .PP
        !           193: You can find out at any time what file name
        !           194: .ul
        !           195: ed
        !           196: is remembering by typing the 
        !           197: .ul
        !           198: file
        !           199: command
        !           200: .UL f .
        !           201: In this example,
        !           202: if you typed
        !           203: .P1
        !           204: f
        !           205: .P2
        !           206: .ul
        !           207: ed
        !           208: would reply
        !           209: .P1
        !           210: junk
        !           211: .P2
        !           212: .SH
        !           213: Reading text from a file \- the Read command ``r''
        !           214: .PP
        !           215: Sometimes you want to read a file into the buffer
        !           216: without destroying anything that is already there.
        !           217: This is done by the
        !           218: .ul
        !           219: read
        !           220: command
        !           221: .UL r .
        !           222: The command
        !           223: .P1
        !           224: r junk
        !           225: .P2
        !           226: will read the file
        !           227: .UL junk
        !           228: into the buffer;
        !           229: it adds it
        !           230: to the end of whatever is already in the buffer.
        !           231: So if you do a read after
        !           232: an edit:
        !           233: .P1
        !           234: e junk
        !           235: r junk
        !           236: .P2
        !           237: the buffer will contain
        !           238: .ul
        !           239: two
        !           240: copies of the text (six lines).
        !           241: .P1
        !           242: Now is the time
        !           243: for all good men
        !           244: to come to the aid of their party.
        !           245: Now is the time
        !           246: for all good men
        !           247: to come to the aid of their party.
        !           248: .P2
        !           249: Like the
        !           250: .UL w
        !           251: and
        !           252: .UL e
        !           253: commands,
        !           254: .UL r
        !           255: prints
        !           256: the
        !           257: number of characters read in, after the reading operation is complete.
        !           258: .PP
        !           259: Generally speaking,
        !           260: .UL r
        !           261: is much less used than
        !           262: .UL e .
        !           263: .SH
        !           264: Exercise 2:
        !           265: .PP
        !           266: Experiment with the
        !           267: .UL e
        !           268: command \-
        !           269: try reading and printing various files.
        !           270: You may get an error
        !           271: .UL ?name ,
        !           272: where
        !           273: .UL name
        !           274: is the name of a file;
        !           275: this means that the file doesn't exist,
        !           276: typically because you spelled the file name wrong,
        !           277: or perhaps that you are not allowed to read or write it.
        !           278: Try alternately reading and appending to see that they work
        !           279: similarly.
        !           280: Verify that
        !           281: .P1
        !           282: ed filename
        !           283: .P2
        !           284: is exactly equivalent to
        !           285: .P1
        !           286: ed
        !           287: e filename
        !           288: .P2
        !           289: What does
        !           290: .P1
        !           291: f filename
        !           292: .P2
        !           293: do?
        !           294: .SH
        !           295: Printing the contents of the buffer \- the Print command ``p''
        !           296: .PP
        !           297: To
        !           298: .ul
        !           299: print
        !           300: or list the contents of the buffer (or parts
        !           301: of it) on the terminal, use the print command
        !           302: .P1
        !           303: p
        !           304: .P2
        !           305: The way this is done is as follows.
        !           306: Specify the lines where
        !           307: you want printing to begin and where you want it to end,
        !           308: separated by a comma, and
        !           309: followed by the letter
        !           310: .UL p .
        !           311: Thus to print the first two lines of the buffer, for
        !           312: example, (that is, lines 1 through 2) say
        !           313: .P1
        !           314: 1,2p   (starting line=1, ending line=2 p)
        !           315: .P2
        !           316: .ul
        !           317: Ed
        !           318: will respond with
        !           319: .P1
        !           320: Now is the time
        !           321: for all good men
        !           322: .P2
        !           323: .PP
        !           324: Suppose you want to print
        !           325: .ul
        !           326: all
        !           327: the lines in the buffer.
        !           328: You could use
        !           329: .UL 1,3p
        !           330: as above if you knew there were exactly
        !           331: 3 lines in the buffer.
        !           332: But in general, you don't
        !           333: know how many there are, so what do you use for the ending
        !           334: line number?
        !           335: .ul
        !           336: Ed
        !           337: provides a shorthand symbol for ``line number of
        !           338: last line in buffer'' \- the dollar sign
        !           339: .UL $ .
        !           340: Use it this
        !           341: way:
        !           342: .P1
        !           343: 1,$p
        !           344: .P2
        !           345: This will print
        !           346: .ul
        !           347: all
        !           348: the lines in the buffer (line 1 to last line.)
        !           349: If you want to stop the printing before it is finished,
        !           350: push the
        !           351: .UC DEL
        !           352: or Delete key;
        !           353: .ul
        !           354: ed
        !           355: will type
        !           356: .P1
        !           357: ?
        !           358: .P2
        !           359: and wait for the next command.
        !           360: .PP
        !           361: To print the
        !           362: .ul
        !           363: last
        !           364: line of the buffer, you could use
        !           365: .P1
        !           366: $,$p
        !           367: .P2
        !           368: but
        !           369: .ul
        !           370: ed
        !           371: lets you abbreviate this to
        !           372: .P1
        !           373: $p
        !           374: .P2
        !           375: You can print any single line by typing the line
        !           376: number followed by a
        !           377: .UL p .
        !           378: Thus
        !           379: .P1
        !           380: 1p
        !           381: .P2
        !           382: produces the response
        !           383: .P1
        !           384: Now is the time
        !           385: .P2
        !           386: which is the first line of the buffer.
        !           387: .PP
        !           388: In fact,
        !           389: .ul
        !           390: ed
        !           391: lets you abbreviate even further:
        !           392: you can print any single line by typing
        !           393: .ul
        !           394: just
        !           395: the line number \- no need to type the letter
        !           396: .UL p .
        !           397: So if you say
        !           398: .P1
        !           399: $
        !           400: .P2
        !           401: .ul
        !           402: ed
        !           403: will print the last line of the buffer.
        !           404: .PP
        !           405: You can also use
        !           406: .UL $
        !           407: in combinations like
        !           408: .P1
        !           409: $\-1,$p
        !           410: .P2
        !           411: which prints the last two lines of the buffer.
        !           412: This helps when you want to see how far you got in typing.
        !           413: .SH
        !           414: Exercise 3:
        !           415: .PP
        !           416: As before, create some text using the
        !           417: .UL a
        !           418: command and
        !           419: experiment with the
        !           420: .UL p
        !           421: command.
        !           422: You will find, for example,
        !           423: that you can't print line 0 or a line beyond
        !           424: the end of the buffer, and that attempts
        !           425: to print a buffer in reverse order by saying
        !           426: .P1
        !           427: 3,1p
        !           428: .P2
        !           429: don't work.

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