fspec(F)                        19 June 1992                        fspec(F)


 Name

    fspec - format specification in text files

 Description

    It is sometimes convenient to maintain text files on the UNIX system with
    non-standard tabs, (that is, tabs which are not set at every eighth
    column).  Such files must generally be converted to a standard format,
    frequently by replacing all tabs with the appropriate number of spaces,
    before they can be processed by UNIX system commands.  A format specifi-
    cation occurring in the first line of a text file specifies how tabs are
    to be expanded in the remainder of the file.

    A format specification consists of a sequence of parameters separated by
    blanks and surrounded by the brackets <: and :>.  Each parameter consists
    of a keyletter, possibly followed immediately by a value.  The following
    parameters are recognized:

    ttabs    The t parameter specifies the tab settings for the file.  The
             value of tabs must be one of the following:

             +  a list of column numbers separated by commas, indicating tabs
                set at the specified columns

             +  a - (dash) followed by an integer n, indicating tabs at
                intervals of n columns

             +  a - (dash) followed by the name of a ``canned'' tab specifi-
                cation


             Standard tabs are specified by t-8, or equivalently, t1,9,17,25,
             and so on. The canned tabs that are recognized are defined by
             the tabs(C) command.

    ssize    The s parameter specifies a maximum line size.  The value of
             size must be an integer.  Size checking is performed after the
             tabs have been expanded, but before the margin is prepended.

    mmargin  The m parameter specifies a number of spaces to be prepended to
             each line.  The value of margin must be an integer.

    d        The d parameter takes no value.  Its presence indicates that the
             line containing the format specification is to be deleted from
             the converted file.

    e        The e parameter takes no value.  Its presence indicates that the
             current format is to prevail only until another format specifi-
             cation is encountered in the file.

    Default values, which are assumed for parameters not supplied, are t-8
    and m0.  If the s parameter is not specified, no size checking is per-
    formed.  If the first line of a file does not contain a format specifica-
    tion, these defaults are assumed for the entire file.

    The following is an example of a line containing a format specification:

       * <:t5,10,15 s72:> *

    If a format specification can be disguised as a comment, it is not neces-
    sary to code the d parameter.

 See also

    ed(C), newform(C), tabs(C)