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. This parameter is ignored for scheme-specified tables.
- 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). This parameter is ignored for
scheme-specified tables.
- 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 scheme specification of the form
:<scheme-name>:<scheme-args>.
- 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.
- icmd=<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.
- ocmd=<cmds>
Specifies processing to be performed on the output table,
after all 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|checksum|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
- checksum
- 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.
This parameter must only be given if omode has its default
value of "out".
- atable=<loc-expr>
Gives the location of the table whose rows will be turned
into an array-valued column. This will generally be an expression giving a URL
or filename that is different for each row of the input table. If table
loading fails for the given location, for instance becase the file is not
found or an HTTP 404 response is received, the array cells in the
corresponding row will be blank.
The first non-blank table loaded defines the array columns to be
added. If subsequent tables have a different structure (do not contain
similar columns in a similar sequence) an error may result. If the external
array tables are not all homogenous in this way, the acmd parameter
can be used to filter them so that they are.
- afmt=<in-format>
Specifies the format of array tables as specified by
parameter
atable. 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. This parameter is ignored for scheme-specified tables.
- astream=true|false
If set true, array tables specified by the
atable
parameter will be read as a stream. It is necessary to give the
afmt
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). This parameter is ignored for
scheme-specified tables.
- acmd=<cmds>
Specifies processing to be performed on array tables as
specified by parameter
atable, 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.
- keepall=true|false
This parameter determines what happens when the
atable parameter does not name a table that can be loaded. If this
parameter is false, the input table row is output with blank values in the
columns supplied by the array tables, so that the output table has the same
number of rows as the input table. If it is true, only rows with successfully
loaded tables are included in the output.
- aparams=<name-list>
Lists the table parameters (per-table metadata) that will
be read from loaded tables and turned into scalar-valued columns in the
output. By default parameters are discarded, but you can include them in the
output by naming them using this parameter.
Parameters are supplied as a space- or comma-separated list.
Matching against table names is case-insensitive, and the asterisk character
"*" may be used as a wildcard to match any sequence of
characters. The list is interpreted relative to the first external table
which is loaded. Supplying the value "*" therefore will
include a column for each parameter in the first loaded table.
- cache=true|false
Determines whether the array data will be cached the
first time an array table is read (true) or re-read from the array table every
time the row is accessed (false). Since the row construction may be an
expensive step, especially if the tables are downloaded, it usually makes
sense to set this true (the default). When true it also enables the metadata
to be adjusted to report constant array length where applicable, which cannot
be done before all the rows have been scanned, and which may enable more
efficient file output. However, if you want to stream the data you can set it
false.
- fixcols=none|dups|all
Determines how input columns are renamed before use in
the output table. The choices are:
- none: columns are not renamed
- dups: columns which would otherwise have duplicate names in the
output will be renamed to indicate which table they came from
- all: all columns will be renamed to indicate which table they came
from
If columns are renamed, the new ones are determined by
suffix*
parameters.
- suffixarray=<label>
If the
fixcols parameter is set so that input
columns are renamed for insertion into the output table, this parameter
determines how the renaming is done. It gives a suffix which is appended to
all renamed columns from the array tables.