Ubuntu Manpage: stilts-tpipe - Performs pipeline processing on a table

NAME

       stilts-tpipe - Performs pipeline processing on a table

SYNOPSIS

       stilts tpipe [ifmt=<in-format>] [istream=true|false] [in=<table>] [cmd=<cmds>]
                    [omode=out|meta|stats|count|cgi|discard|topcat|samp|tosql|gui] [out=<out-
                    table>] [ofmt=<out-format>]

DESCRIPTION

tpipe performs all kinds of general purpose manipulations which take one table as input.
It is extremely flexible, and can do the following things amongst others:

* calculate statistics

* display metadata

* select rows in various ways, including algebraically

* define new columns as algebraic functions of old ones

* delete or rearrange columns

* sort rows

* convert between table formats
and combine these operations. You can think of it as a supercharged table copying tool.

The basic operation of tpipe is that it reads an input table, performs zero or more
processing steps on it, and then does something with the output. There are therefore three
classes of things you need to tell it when it runs:

Input table location Specified by the in, ifmt and istream parameters.

Processing steps Either provide a string giving steps as the value of one or more cmd
parameters, or the name of a file containing the steps using the script parameter. The
steps that you can perform are described in SUN/256.

Output table destination What happens to the output table is determined by the value of
the omode parameter. By default, omode=out, in which case the table is written to a new
table file in a format determined by ofmt. However, you can do other things with the
result such as calculate the per-column statistics (omode=stats), view only the table and
column metadata (omode=meta), display it directly in TOPCAT (omode=topcat) etc. See
SUN/256 for a more detailed explanation of these ideas.

The parameters mentioned above are listed in detail in the next section.

OPTIONS

ifmt=<in-format>
Specifies the format of the input table as specified by parameter in. The known
formats are listed in SUN/256. This flag can be used if you know what format your
table is in. If it has the special value (auto) (the default), then an attempt will
be made to detect the format of the table automatically. This cannot always be done
correctly however, in which case the program will exit with an error explaining
which formats were attempted.

istream=true|false
If set true, the input table specified by the in parameter will be read as a
stream. It is necessary to give the ifmt parameter in this case. Depending on the
required operations and processing mode, this may cause the read to fail (sometimes
it is necessary to read the table more than once). It is not normally necessary to
set this flag; in most cases the data will be streamed automatically if that is the
best thing to do. However it can sometimes result in less resource usage when
processing large files in certain formats (such as VOTable).

in=<table>
The location of the input table. This may take one of the following forms:

* A filename.

* A URL.

* The special value "-", meaning standard input. In this case the input format
must be given explicitly using the ifmt parameter. Note that not all formats
can be streamed in this way.

* A system command line with either a "<" character at the start, or a "|"
character at the end ("<syscmd" or "syscmd|"). This executes the given pipeline
and reads from its standard output. This will probably only work on unix-like
systems.
In any case, compressed data in one of the supported compression formats (gzip,
Unix compress or bzip2) will be decompressed transparently.

cmd=<cmds>
Specifies processing to be performed on the input table as specified by parameter
in, before any other processing has taken place. The value of this parameter is one
or more of the filter commands described in SUN/256. If more than one is given,
they must be separated by semicolon characters (";"). This parameter can be
repeated multiple times on the same command line to build up a list of processing
steps. The sequence of commands given in this way defines the processing pipeline
which is performed on the table.

Commands may alteratively be supplied in an external file, by using the indirection
character '@'. Thus a value of "@filename" causes the file filename to be read for
a list of filter commands to execute. The commands in the file may be separated by
newline characters and/or semicolons, and lines which are blank or which start with
a '#' character are ignored.

omode=out|meta|stats|count|cgi|discard|topcat|samp|tosql|gui
The mode in which the result table will be output. The default mode is out, which
means that the result will be written as a new table to disk or elsewhere, as
determined by the out and ofmt parameters. However, there are other possibilities,
which correspond to uses to which a table can be put other than outputting it, such
as displaying metadata, calculating statistics, or populating a table in an SQL
database. For some values of this parameter, additional parameters (<mode-args>)
are required to determine the exact behaviour.

Possible values are

* out

* meta

* stats

* count

* cgi

* discard

* topcat

* samp

* tosql

* gui
Use the help=omode flag or see SUN/256 for more information.

out=<out-table>
The location of the output table. This is usually a filename to write to. If it is
equal to the special value "-" (the default) the output table will be written to
standard output.

This parameter must only be given if omode has its default value of "out".

ofmt=<out-format>
Specifies the format in which the output table will be written (one of the ones in
SUN/256 - matching is case-insensitive and you can use just the first few letters).
If it has the special value "(auto)" (the default), then the output filename will
be examined to try to guess what sort of file is required usually by looking at the
extension. If it's not obvious from the filename what output format is intended, an
error will result.