.help fields Jan86 proto
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NAME
fields -- extract selected fields from a list.
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USAGE
fields files fields
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PARAMETERS
.ls files
File or files from which the fields are to be extracted.
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.ls fields
The fields to be extracted.  
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.ls lines = "1-"
The lines from which the fields are to be extracted.  If multiple files are 
being extracted, the same lines apply to each file.
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.ls quit_if_missing = no
This flag determines the task behavior when a field is missing from the
specified line.  If \fBquit_if_missing\fR = yes, the task exits and an error 
is reported.
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.ls print_file_names = no
If \fBprint_file_name\fR = yes, the first string of each output line of
extracted fields is the file name.  
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DESCRIPTION
The list processing tool \fIfields\fR is used to extract whitespace
separated fields from the specified files and lines.
The input to this task can be either the standard input or a list of
files; output is a new list of the extracted fields.

The fields of a line are numbered from 1 up to a newline character; those
fields to be extracted are specified as a range of numbers.
If a specified field is missing from a selected
line the action taken is determined by the \fBquit_if_missing\fR flag;
\fIfields\fR will either continue processing after printing a warning
message, or call an error and exit.
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EXAMPLES
1. Reverse the order of the 5 columns in list file "list".
.nf

	cl> fields list 5-1 > newlist
.fi

2. Extract columns 1 and 3 from file "newlist" and pipe them to task
\fIgraph\fR.
.nf

	cl> fields newlist 1,3 | graph
.fi
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REVISIONS
.ls FIELDS V2.11
The default value for the \fIlines\fR parameter was changed to an open
upper limit.
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SEE ALSO
joinlines, xtools.ranges
.endhelp
