HELPLIB.HLB  —  DIFFERENCES
    Compares the contents of two disk files and displays a listing of
    the records that do not match.

    Format

      DIFFERENCES  input1-filespec [input2-filespec]

1  –  Parameters

 input1-filespec

    Specifies the first file to be compared. The file specification
    must include a file name and a file type. The asterisk (*)  and
    the percent sign (%)  wildcard characters are not allowed.

 input2-filespec

    Specifies the second file to be compared. Unspecified fields
    default to the corresponding fields in the input1-filespec
    parameter. The asterisk (*)  and the percent sign (%) wildcard
    characters are not allowed.

    If you do not specify a secondary input file, the DIFFERENCES
    command uses the next lower version of the primary input file.

2  –  Qualifiers

2.1    /CHANGE_BAR

       /CHANGE_BAR[=([change-char][,[NO]NUMBER])]

    Marks differences using the specified character. The /CHANGE_BAR
    qualifier displays output that depends on where the qualifier is
    placed. The following examples describe the result of /CHANGE_BAR
    qualifier placement.

    The following placement displays the latest version of input.file
    with the pound sign (#)  preceding any lines that differ from the
    preceding version of input.file:

    $ DIFFERENCES input.file/CHANGE_BAR=#

    The following placement displays input.file;2 with the pound sign
    (#)  preceding any lines that differ from input.file;1:

    $ DIFFERENCES input.file;1  input.file;2 /CHANGE_BAR=#

    The following placement displays input.file;1 with the pound sign
    (#)  preceding any lines that differ from input.file;2:

    $ DIFFERENCES input.file;1/CHANGE_BAR=#  input.file;2

    The following placement displays input.file;1 with the percent
    sign (%)  preceding any lines that differ from input.file;2, and
    also displays input.file;2 with the pound sign (#)  preceding any
    lines that differ from input.file;1:

    $ DIFFERENCES input.file;1/CHANGE_BAR=% input.file;2/CHANGE_BAR=#

    o  If you do not specify a change bar character, the default is
       an exclamation point (!)  for ASCII output.

    o  If you specify hexadecimal or octal output (see the
       description of the /MODE qualifier), the change bar character
       is ignored and differences are marked by a "***CHANGE***"
       string in the record header. The keyword NONUMBER suppresses
       line numbers in the listing.

    o  If neither the NUMBER nor the NONUMBER keyword is specified,
       the default is controlled by the /[NO]NUMBER command
       qualifier.

    o  If you specify only one option, you can omit the parentheses.

    o  If you use an exclamation point (!)  as the specified
       character, you must enclose it in quotation marks (" ");  for
       example, /CHANGE_BAR=("!",NUMBER).

2.2    /COMMENT_DELIMITER

       /COMMENT_DELIMITER[=(character[,...])]

    Ignores characters on a line to the right of (and including) a
    specified comment character.

    If you specify just one character, you can omit the parentheses.
    Lowercase characters are automatically converted to uppercase
    unless they are enclosed in quotation marks. Nonalphanumeric
    characters (such as ! and ,) must be enclosed in quotation
    marks. Multicharacter comment characters are not allowed. You
    can specify up to 32 comment characters by typing the character
    itself or one of the following keywords. (Keywords can be
    abbreviated provided that the resultant keyword is not ambiguous
    and has at least 2 characters; single letters are treated as
    delimiters.)

    Keyword          Character

    COLON            Colon (:)
    COMMA            Comma (,)
    EXCLAMATION      Exclamation point (!)
    FORM_FEED        Form feed
    LEFT             Left bracket ([)
    RIGHT            Right bracket (])
    SEMI_COLON       Semicolon (;)
    SLASH            Slash (/)
    SPACE            Space
    TAB              Tab

    If you specify the /COMMENT_DELIMITER qualifier, the
    /IGNORE=COMMENTS qualifier is implicitly also included.

    If both the uppercase and lowercase forms of a letter are to be
    used as comment characters, the letter must be specified twice,
    once in uppercase and once in lowercase. If you do not include
    either a comment character or a keyword with the /COMMENT_
    DELIMITER qualifier, the DIFFERENCES command assumes a default
    comment character based on the file type. For some file types
    (.COB and .FOR), the default comment characters are considered
    valid delimiters only if they appear in the first column of a
    line.

    The following characters are the default comment delimiters for
    files with the specified file types:

    File Type        Default Comment Character

    .B2S, .B32,      !
    .BAS, .BLI
    .CBL, .CMD       ! and ;
    .COB             * or / in the first column
    .COM, .COR       !
    .FOR             ! anywhere and C, D, c, d in the first column
    .HLP             !
    .MAC, .MAR       ;
    .R32, .REQ       !

2.3    /EXACT

    Use with the /PAGE=SAVE and /SEARCH qualifiers to specify a
    search string that must match the search string exactly and must
    be enclosed with quotation marks (" ").

    If you specify the /EXACT qualifier without the /SEARCH
    qualifier, exact search mode is enabled when you set the search
    string with the Find (E1) key.

2.4    /HIGHLIGHT

       /HIGHLIGHT[=keyword]

    Use with the /PAGE=SAVE and /SEARCH qualifiers to specify the
    type of highlighting you want when a search string is found. When
    a string is found, the entire line is highlighted. You can use
    the following keywords: BOLD, BLINK, REVERSE, and UNDERLINE. BOLD
    is the default highlighting.

2.5    /IGNORE

       /IGNORE=(keyword[,...])

    Inhibits the comparison of the specified characters, strings,
    or records; also controls whether the comparison records are
    output to the listing file as edited records or exactly as they
    appeared in the input file. If you specify only one keyword, you
    can omit the parentheses. The keyword parameter refers to either
    a character or a keyword. The first set of keywords determines
    what, if anything, is ignored during file comparison; the second
    set of keywords determines whether or not ignored characters are
    included in the output. The following keywords are valid options
    for the /IGNORE qualifier:

    Keyword          Item Ignored

    BLANK_LINES      Blank lines between data lines.

    CASE             Case of the text being compared.

    COMMENTS         Data following a comment character. (Use the
                     /COMMENT_DELIMITER qualifier to designate one or
                     more nondefault comment delimiters.)

    FORM_FEEDS       Form feed character.

    HEADER[=n]       Defines n records of the file as header records,
                     beginning with a record whose first character is
                     a form feed. The first record is not ignored if
                     the only character it contains is a form feed.
                     (n indicates the header size and defaults to 2.
                     A record containing only a single form feed is
                     not counted in n.)

    SPACING          Extra spaces or tabs within data lines.

    TRAILING_SPACES  Space and tab characters at the end of a data
                     line.

    WHITE_SPACE      All spaces and tab characters.

    Keyword          Status of Ignored Items in Output

    EDITED           Omits ignored characters from the output
                     records.

    EXACT            Includes ignored characters in the output
                     records.

    PRETTY           Formats output records.

    Each data line is checked for COMMENTS, FORM_FEEDS, HEADER,
    and SPACING before it is tested for TRAILING_SPACES and then
    BLANK_LINES. Therefore, if you direct the DIFFERENCES command to
    ignore COMMENTS, TRAILING_SPACES, and BLANK_LINES, it ignores a
    record that contains several spaces or blank lines followed by a
    comment.

    By default, the DIFFERENCES command compares every character
    in each file and reports all differences. Also, by default, the
    DIFFERENCES command lists records in the output file with all
    ignored characters deleted.

    If you specify the /PARALLEL qualifier, output records are always
    formatted. The following table shows the corresponding output for
    the various characters that are being translated:

    Character              Formatted Output

    Tab (Ctrl/I)           1-8 spaces
    Return (Ctrl/M)        <CR>
    Line feed (Ctrl/J)     <LF>
    Vertical tab (Ctrl/K)  <VT>
    Form feed (Ctrl/L)     <FF>
    Other nonprinting      . (period)
    characters

2.6    /MATCH

       /MATCH=size

    Specifies the number of records that should indicate matching
    data after a difference is found. By default, after the
    DIFFERENCES command finds unmatched records, it assumes that the
    files once again match after it finds three sequential records
    that match. Use the /MATCH qualifier to override the default
    match size of 3.

    You can increase the /MATCH qualifier value if you feel that
    the DIFFERENCES command is incorrectly matching sections of
    the master and revision input files after it has detected a
    difference.

2.7    /MAXIMUM_DIFFERENCES

       /MAXIMUM_DIFFERENCES=n

    Terminates the DIFFERENCES command after the specified number of
    unmatched records (specified with the n parameter) is found.

    The number of unmatched records is determined by finding the
    maximum number of difference records for each difference section
    and adding them together.

    If the DIFFERENCES command reaches the maximum number of
    differences that you specify, it will output only those records
    that were detected before the maximum was reached. Also, it will
    output, at most, one listing format and return a warning message.

    By default, there is no maximum number of differences. All
    records in the specified input files are compared.

2.8    /MERGED

       /MERGED[=n]

    Specifies that the output file contain a merged list of
    differences with the specified number of matched records
    listed after each group of unmatched records. The value of the
    parameter n must be less than or equal to the number specified
    in the /MATCH qualifier. By default, the DIFFERENCES command
    produces a merged listing with one matched record listed after
    each set of unmatched records (that is, /MERGED=1). If the
    /MERGED, /SEPARATED, or /PARALLEL qualifier is not specified,
    the resulting output is merged, with one matched record following
    each unmatched record.

    Use the /MERGED qualifier to override the default value of the
    parameter n, or to include a merged listing with other types of
    output.

2.9    /MODE

       /MODE=(radix[,...])

    Specifies the format of the output. You can request that the
    output be formatted in one or more radix modes by specifying the
    following keywords, which may be abbreviated: ASCII (default),
    HEXADECIMAL, or OCTAL. If you specify only one radix, you can
    omit the parentheses.

    By default, the DIFFERENCES command writes the output file in
    ASCII. If you specify more than one radix, the output listing
    contains the file comparison in each specified radix. When you
    specify two or more radix modes, separate them with commas.

    If you specify the /PARALLEL or the /SLP qualifier, the /MODE
    qualifier is ignored for that listing form.

2.10    /NUMBER

       /NUMBER (default)
       /NONUMBER

    Includes line numbers in the listing of DIFFERENCES.

2.11    /OUTPUT

       /OUTPUT[=filespec]

    Specifies an output file to receive the list of differences.
    By default, the output is written to the current SYS$OUTPUT
    device. If the filespec parameter is not specified, the output
    is directed to the first input file with a file type .DIF. The
    asterisk (*) and the percent sign (%) wildcard characters are not
    allowed.

    When you specify the /OUTPUT qualifier, you can control the
    defaults applied to the output file specification as described
    in the OpenVMS User's Manual. The default output file type is
    .DIF.

2.12    /PAGE

       /PAGE[=keyword]
       /NOPAGE (default)

    Controls the display of difference information on the screen.

    You can use the following keywords with the /PAGE qualifier:

    CLEAR_SCREEN   Clears the screen before each page is displayed.

    SCROLL         Displays information one line at a time.

    SAVE[=n]       Enables screen navigation of information, where n
                   is the number of pages to store.

    The /PAGE=SAVE qualifier allows you to navigate through screens
    of information. The /PAGE=SAVE qualifier stores up to 5 screens
    of up to 255 columns of information. When you use the /PAGE=SAVE
    qualifier, you can use the following keys to navigate through the
    information:

    Key Sequence              Description

    Up arrow key, Ctrl/B      Scroll up one line.
    Down arrow key            Scroll down one line.
    Left arrow key            Scroll left one column.
    Right arrow key           Scroll right one column.
    Find (E1)                 Specify a string to find when the
                              information is displayed.
    Insert Here (E2)          Scroll right one half screen.
    Remove (E3)               Scroll left one half screen.
    Select (E4)               Toggle 80/132 column mode.
    Prev Screen (E5)          Get the previous page of information.
    Next Screen (E6),         Get the next page of information.
    Return, Enter, Space
    F10, Ctrl/Z               Exit. (Some utilities define these
                              differently.)
    Help (F15)                Display utility help text.
    Do (F16)                  Toggle the display to oldest/newest
                              page.
    Ctrl/W                    Refresh the display.

    The /PAGE qualifier is not compatible with the /OUTPUT qualifier.

2.13    /PARALLEL

       /PARALLEL[=n]

    Lists the records with differences side by side. The value of
    the parameter n specifies the number of matched records to merge
    after each unmatched record; it must be a non-negative decimal
    number less than or equal to the number specified in the /MATCH
    qualifier.

    By default, the DIFFERENCES command does not list records after
    each list of unmatched records. Also by default, the DIFFERENCES
    command creates only a list of merged differences.

2.14    /SEARCH

       /SEARCH="string"

    Use with the /PAGE=SAVE qualifier to specify a string that you
    want to find in the information being displayed. Quotation marks
    are required for the /SEARCH qualifier, if you include spaces in
    the text string.

    You can also dynamically change the search string by pressing the
    Find key (E1) while the information is being displayed. Quotation
    marks are not required for a dynamic search.

2.15    /SEPARATED

       /SEPARATED[=MASTER, REVISION]

    Lists sequentially only the records from the specified file
    that contain differences. Use the MASTER keyword to list the
    differences in the first input file specified; use the REVISION
    keyword to list the differences in the second input file
    specified.

    By default, the DIFFERENCES command creates only a merged list of
    differences.

2.16    /SLP

    Requests that the DIFFERENCES command produce an output file
    suitable for input to the SLP editor. If you use the /SLP
    qualifier, you cannot specify any of the following output file
    qualifiers: /MERGED, /PARALLEL, /SEPARATED, or /CHANGE_BAR.

    Use the output file produced by the SLP qualifier as input to
    SLP to update the master input file, that is, to make the master
    input file match the revision input file.

    When you specify the /SLP qualifier and you do not specify the
    /OUTPUT qualifier, the DIFFERENCES command writes the output file
    to a file with the same file name as the master input file with
    the file type DIF.

2.17    /WIDTH

       /WIDTH=n

    Specifies the width of the lines in the output file. The default
    is 132 characters. If output is written to the terminal, the
    /WIDTH qualifier is ignored and the terminal line width is used.

    Use the SET TERMINAL command to change the terminal line width.

2.18    /WINDOW

       /WINDOW=size

    Searches the number of records specified by the size parameter,
    before a record is declared as unmatched. By default, the
    DIFFERENCES command searches to the ends of both input files
    before listing a record as unmatched.

    The window size is the minimum size of a differences section
    that will cause the DIFFERENCES command to lose synchronization
    between the two input files.

2.19    /WRAP

       /WRAP
       /NOWRAP (default)

    Use with the /PAGE=SAVE qualifier to limit the number of columns
    to the width of the screen and to wrap lines that extend beyond
    the width of the screen to the next line.

    The /NOWRAP qualifier extends lines beyond the width of the
    screen and can be seen when you use the scrolling (left and
    right) features provided by the /PAGE=SAVE qualifier.

3  –  Examples

    1.$ DIFFERENCES EXAMPLE.TXT
      ************
      File DISK1:[CHRIS.TEXT]EXAMPLE.TXT;2
          1   DEMONSTRATION
          2   OF V7.3 DIFFERENCES
          3   UTILITY
      ******
      File DISK1:[CHRIS.TEXT]EXAMPLE.TXT;1
          1   DEMONSTRETION
          2   OF VMS DIFFERENCES
          3   UTILITY
      ************
      Number of difference sections found: 1
      Number of difference records found: 2
      DIFFERENCES/ IGNORE=()/MERGED=1-
             DISK1:[CHRIS.TEXT]EXAMPLE.TXT;2-
             DISK1:[CHRIS.TEXT]EXAMPLE.TXT;1

      In this example, the DIFFERENCES command compares the contents
      of the two most recent versions of the file EXAMPLE.TXT in the
      current default directory. The DIFFERENCES command compares
      every character in every record and displays the results at the
      terminal.

    2.$ DIFFERENCES/WIDTH=80/MODE=(HEX,ASCII) EXAMPLE.TXT/CHANGE_BAR
      ************
      File DISK1:[CHRIS.TEXT]EXAMPLE.TXT;2
          1 ! DEMONSTRATION
          2 ! OF V7.3 DIFFERENCES
          3   UTILITY
      ************
      ************
      File DISK1:[CHRIS.TEXT]EXAMPLE.TXT;2
      RECORD NUMBER 1 (00000001) LENGTH 14 (0000000E)  ***CHANGE***
           204E 4F495441 5254534E 4F4D4544 DEMONSTRATION .. 000000
      RECORD NUMBER 2 (00000002) LENGTH 19 (00000013)  ***CHANGE***
       4E455245 46464944 20302E33 5620464F OF V7.3 DIFFEREN 000000
                                    534543 CES............. 000010
      RECORD NUMBER 3 (00000003) LENGTH 7 (00000007)
                           595449 4C495455 UTILITY......... 000000
      ************
      Number of difference sections found: 1
      Number of difference records found: 2
      DIFFERENCES /WIDTH=80/MODE=(HEX,ASCII)
             DISK1:[CHRIS.TEXT]EXAMPLE.TXT;2/CHANGE_BAR-
             DISK1:[CHRIS.TEXT]EXAMPLE.TXT;1

      The DIFFERENCES command compares the same files as in
      Example 1, but lists the differences in both hexadecimal and
      ASCII formats. The command also specifies that default change
      bars be used in the output. The default change bar notation for
      the hexadecimal output is ***CHANGE***. For the ASCII output,
      the default change bar character is the exclamation point.

    3.$ DIFFERENCES/OUTPUT BOSTON::DISK2:TEST.DAT OMAHA::DISK1:[PGM]TEST.DAT

      The DIFFERENCES command compares two remote files and displays
      any differences found. The first file is TEST.DAT on remote
      node BOSTON. The second file is also named TEST.DAT on remote
      node OMAHA. The DIFFERENCES output is located in the file
      DISK1:[PGM]TEST.DIF.
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