I want to do some analysis!
Well, you're going to need some data. Here's how you get it:
The easiest way to get a list of files is by using the linemode client 'find' command. Here's it's help screen:
dflath@noric09> /afs/slac/g/glast/ground/bin/datacat -h find
Command-specific help for command find
Usage: datacat find [-options] <logical folder>
parameters:
<logical folder> Logical Folder Path at which to begin performing the search.
options:
--recurse Recurse sub-folders
--search-folders Search for datasets inside folder(s)
-search-groups Search in groups. This option is superceeded by the -G (-group) option if they are both supplied.
--group <group name> Dataset Group under which to search for datasets.
--site <site name> Name of Site to search. May be used multiple times to specify a list of sites in which case order is taken as preference. Defaults to the Master-location if not provided.
--filter <filter expression> Criteria by which to filter datasets. ie: 'DatasetDataType=="MERIT" && nMetStart>=257731220 && nMetStop <=257731580'
--sort <meta name> Name of meta-data field to sort on. May be used multiple times to specify a list of fields to sort on. Order determines presidence.
Thanks for nothing, that's the part that confuses me!
Alright, here's what it all means:
Arguments to 'find' command:
Argument |
Explanation |
|---|---|
<logical folder> |
This parameter is required and comes after all options are specified. Replace it with the Data Catalog folder path where you want to begin your search. |
--recurse |
If you specify this option, the find command will traverse the folder tree under <logical folder> in it's quest to provide you with the data you desire. |
--search-folders |
Tells find to look inside the folder (or folders if --recurse specified) and consider datasets that live there. In general, datasets live in groups, and this option is not used. |
--search-groups |
Tells find to look inside all dataset groups in the specified folder (or folder tree if using --recurse) for your files. May be combined with --search-folders and --recurse. |
--group <group name> |
Tells find to look inside groups only if they have the name specified by <group name>. May be used with --recurse to search in groups of the given name in a folder tree. |
--site <site name> |
|
--filter <filter expression> |
Also known as "search criteria" is an expression using logical operators, meta-data fields and constant values on which to filter the output results. |
--sort <meta name> |
Specifies the name of the specific meta-data field on which to sort the output results. May be used multiple times to specify a list of fields to sort on where order indicates preference. |
*Important note: At least one of --search-folders, --search-groups, --group <group name> must be specified.
<site name> Valid values:
SLAC_XROOT |
XROOT servers at SLAC. Almost everything lives here. |
SLAC |
NFS (or AFS) at SLAC. Some FT1 and FT2 data are stored here until the ftools learn to read from XROOT. |
IN2P3 |
Some Monte Carlo data is stored at Lyon |
IN2P3_HPSS |
Lyon Monte Carlo backups |
UW |
University of Washington. |
<filter expression> Specifics:
A logical expression used to select datasets that meet specific criteria. Here's a loose grammar which defines expressions:
Expr ::= Expr
Expr ::= '(' Expr ')'
Expr ::= '!' Expr
Expr ::= Expr LogOp Expr
LogOp ::= '&&' | '||'
Expr ::= Comparable CmpOp Comparable
CmpOp ::= '==' | '!=' | '>=' | '<='
Comparable ::= "String" -- a String constant must be enclosed in double quotes
Comparable ::= Number
Comparable ::= Identifier
Comparable ::= UnOp Comparable
UnOp ::= '-' | '+'
Comparable ::= Comparable BinOp Comparable
BinOp ::= '/' | '*' | '+' | '-'