diff options
Diffstat (limited to 'doc/gawktexi.in')
| -rw-r--r-- | doc/gawktexi.in | 63 |
1 files changed, 36 insertions, 27 deletions
diff --git a/doc/gawktexi.in b/doc/gawktexi.in index 7c1f7120..a5c65a3e 100644 --- a/doc/gawktexi.in +++ b/doc/gawktexi.in @@ -24082,13 +24082,13 @@ may be separated by commas, and ranges of characters can be separated with dashes. The list @samp{1-8,15,22-35} specifies characters 1 through 8, 15, and 22 through 35. -@item -f @var{list} -Use @var{list} as the list of fields to cut out. - @item -d @var{delim} Use @var{delim} as the field-separator character instead of the TAB character. +@item -f @var{list} +Use @var{list} as the list of fields to cut out. + @item -s Suppress printing of lines that do not contain the field delimiter. @end table @@ -24098,6 +24098,10 @@ function (@pxref{Getopt Function}) and the @code{join()} library function (@pxref{Join Function}). +The current POSIX version of @command{cut} has options to cut fields based on +both bytes and characters. This version does not attempt to implement those options, +as @command{awk} works exclusively in terms of characters. + The program begins with a comment describing the options, the library functions needed, and a @code{usage()} function that prints out a usage message and exits. @code{usage()} is called if invalid arguments are @@ -24118,9 +24122,9 @@ supplied: @c file eg/prog/cut.awk # Options: +# -c list Cut characters # -f list Cut fields # -d c Field delimiter character -# -c list Cut characters # # -s Suppress lines without the delimiter # @@ -24192,7 +24196,7 @@ incorrect---@command{awk} would separate fields with runs of spaces, TABs, and/or newlines, and we want them to be separated with individual spaces. To this end, we save the original space character in the variable -@code{fs} for later use; after setting @code{FS} to @code{"[ ]"} we can't +@code{fs} for later use; after setting @code{FS} to @code{@w{"[ ]"}} we can't use it directly to see if the field delimiter character is in the string. Also remember that after @code{getopt()} is through @@ -24519,9 +24523,9 @@ Note the comment about invocation: Because several of the options overlap with @command{gawk}'s, a @option{--} is needed to tell @command{gawk} to stop looking for options. -Next comes the code that handles the @command{egrep}-specific behavior. If no -pattern is supplied with @option{-e}, the first nonoption on the -command line is used. +Next comes the code that handles the @command{egrep}-specific behavior. +@command{egrep} uses the first nonoption on the command line is used. +if no pattern is supplied with @option{-e}. If the pattern is empty, that means no pattern was supplied, so it's necessary to print an error message and exit. The @command{awk} command-line arguments up to @code{ARGV[Optind]} @@ -24604,13 +24608,13 @@ the code checks this condition by looking at the values of is not over the full line, @code{matches} is set to zero (false). If the user -wants lines that did not match, the sense of @code{matches} is inverted -using the @samp{!} operator. @code{fcount} is incremented with the value of +wants lines that did not match, we invert the sense of @code{matches} +using the @samp{!} operator. We then increment @code{fcount} with the value of @code{matches}, which is either one or zero, depending upon a successful or unsuccessful match. If the line does not match, the @code{next} statement just moves on to the next input line. -A number of additional tests are made, but they are only done if we +We make a number of additional tests, but only if we are not counting lines. First, if the user only wants the exit status (@code{no_print} is true), then it is enough to know that @emph{one} line in this file matched, and we can skip on to the next file with @@ -25122,7 +25126,9 @@ Here is an implementation of @command{split} in @command{awk}. It uses the @code{getopt()} function presented in @ref{Getopt Function}. The program begins with a standard descriptive comment and then -a @code{usage()} function describing the options: +a @code{usage()} function describing the options. The variable +@code{common} keeps the function's lines short so that they +look nice on the page: @cindex @code{split.awk} program @example @@ -25142,10 +25148,12 @@ a @code{usage()} function describing the options: @c endfile @end ignore @c file eg/prog/split.awk -function usage() + +function usage( common) @{ - print("usage: split [-l count] [-a suffix-len] [file [outname]]") > "/dev/stderr" - print(" split [-b N[k|m]] [-a suffix-len] [file [outname]]") > "/dev/stderr" + common = "[-a suffix-len] [file [outname]]" + printf("usage: split [-l count] %s\n", common) > "/dev/stderr" + printf(" split [-b N[k|m]] %s\n", common) > "/dev/stderr" exit 1 @} @c endfile @@ -25610,7 +25618,8 @@ the options and their meanings in comments: function usage() @{ - print("Usage: uniq [-udc [-f fields] [-s chars]] [ in [ out ]]") > "/dev/stderr" + print("Usage: uniq [-udc [-f fields] [-s chars]] " \ + "[ in [ out ]]") > "/dev/stderr" exit 1 @} @@ -25629,7 +25638,7 @@ so that the @code{getopt()} function can parse the options: @example @c file eg/prog/uniq.awk -# As of 2020, '+' can be used as option character in addition to '-' +# As of 2020, '+' can be used as the option character in addition to '-' # Previously allowed use of -N to skip fields and +N to skip # characters is no longer allowed, and not supported by this version. @@ -25878,7 +25887,7 @@ For the purposes of @file{wc.awk}, it's enough to know that the extension is loaded with the @code{@@load} directive, and the additional function we will use is called @code{mbs_length()}. This function returns the -number of bytes in a string, and not the number of characters. +number of bytes in a string, not the number of characters. The @code{"mbs"} extension comes from the @code{gawkextlib} project. @xref{gawkextlib} for more information. @@ -25897,23 +25906,23 @@ input. If there are multiple files, it also prints total counts for all the files. The options and their meanings are as follows: @table @code -@item -l -Count only lines. - -@item -w -Count only words. -A ``word'' is a contiguous sequence of nonwhitespace characters, separated -by spaces and/or TABs. Luckily, this is the normal way @command{awk} separates -fields in its input data. - @item -c Count only bytes. Once upon a time, the @samp{c} in this option stood for ``characters.'' But, as explained earlier, bytes and character are no longer synonymous with each other. +@item -l +Count only lines. + @item -m Count only characters. + +@item -w +Count only words. +A ``word'' is a contiguous sequence of nonwhitespace characters, separated +by spaces and/or TABs. Luckily, this is the normal way @command{awk} separates +fields in its input data. @end table Implementing @command{wc} in @command{awk} is particularly elegant, |