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Diffstat (limited to 'doc/gawk.texi')
| -rw-r--r-- | doc/gawk.texi | 24 |
1 files changed, 17 insertions, 7 deletions
diff --git a/doc/gawk.texi b/doc/gawk.texi index 2a5565c9..c30c2808 100644 --- a/doc/gawk.texi +++ b/doc/gawk.texi @@ -7149,6 +7149,8 @@ shell, without any quotes, the @samp{\} gets deleted, so @command{awk} figures that you really want your fields to be separated with TABs and not @samp{t}s. Use @samp{-v FS="t"} or @samp{-F"[t]"} on the command line if you really do want to separate your fields with @samp{t}s. +Use @samp{-F '\t'} when not in compatibility mode to specify that TABs +separate fields. As an example, let's use an @command{awk} program file called @file{edu.awk} that contains the pattern @code{/edu/} and the action @samp{print $1}: @@ -7299,7 +7301,7 @@ root @noindent on an incorrect implementation of @command{awk}, while @command{gawk} -prints something like: +prints the full first line of the file, something like: @example root:nSijPlPhZZwgE:0:0:Root:/: @@ -7352,7 +7354,7 @@ root @noindent on an incorrect implementation of @command{awk}, while @command{gawk} -prints something like: +prints the full first line of the file, something like: @example root:nSijPlPhZZwgE:0:0:Root:/: @@ -7489,7 +7491,7 @@ haven't been introduced yet. BEGIN @{ FIELDWIDTHS = "9 6 10 6 7 7 35" @} NR > 2 @{ idle = $4 - sub(/^ */, "", idle) # strip leading spaces + sub(/^ +/, "", idle) # strip leading spaces if (idle == "") idle = 0 if (idle ~ /:/) @{ @@ -7647,6 +7649,8 @@ if (substr($i, 1, 1) == "\"") @{ As with @code{FS}, the @code{IGNORECASE} variable (@pxref{User-modified}) affects field splitting with @code{FPAT}. +Assigning a value to @code{FPAT} overrides field splitting +with @code{FS} and with @code{FIELDWIDTHS}. Similar to @code{FIELDWIDTHS}, the value of @code{PROCINFO["FS"]} will be @code{"FPAT"} if content-based field splitting is being used. @@ -7670,6 +7674,12 @@ FPAT = "([^,]*)|(\"[^\"]+\")" Finally, the @code{patsplit()} function makes the same functionality available for splitting regular strings (@pxref{String Functions}). +To recap, @command{gawk} provides three independent methods +to split input records into fields. @command{gawk} uses whichever +mechanism was last chosen based on which of the three +variables---@code{FS}, @code{FIELDWIDTHS}, and @code{FPAT}---was +last assigned to. + @node Multiple Line @section Multiple-Line Records @@ -9700,7 +9710,7 @@ It then sends the list to the shell for execution. @c ENDOFRANGE reout @node Special Files -@section Special @value{FFN} in @command{gawk} +@section Special @value{FFN}s in @command{gawk} @c STARTOFRANGE gfn @cindex @command{gawk}, file names in @@ -11924,7 +11934,7 @@ made of characters and is therefore also a string. Thus, for example, the string constant @w{@code{" +3.14"}}, when it appears in program source code, is a string---even though it looks numeric---and -is @emph{never} treated as number for comparison +is @emph{never} treated as a number for comparison purposes. In short, when one operand is a ``pure'' string, such as a string @@ -29989,7 +29999,7 @@ to follow. @quotation Math class is tough! -@author Late 1980's Barbie +@author Teen Talk Barbie (July, 1992) @end quotation This @value{SECTION} provides a high level overview of the issues @@ -30615,7 +30625,7 @@ values. The default for @command{awk} is to use double-precision floating-point values. @item -In the 1980's, Barbie mistakenly said ``Math class is tough!'' +In the early 1990's, Barbie mistakenly said ``Math class is tough!'' While math isn't tough, floating-point arithmetic isn't the same as pencil and paper math, and care must be taken: |