== Requirement Expression Syntax ==

The syntax of the requirement expressions is defined as: 

{{{
stmt::= expr
expr::= VARIABLE '=' INTEGER
         | VARIABLE '>' INTEGER
         | VARIABLE '<' INTEGER
         | VARIABLE '=' STRING
         | expr '&' expr
         | expr '|' expr
         | '!' expr
         | '(' expr ')'
}}}

Each expression is evaluated to 1 (TRUE) or 0 (FALSE). Only those hosts for which the requirement expression is evaluated to TRUE will be considered to execute the job.

Logical operators are as expected ( less '<', greater '>', '&' AND, '|' OR, '!' NOT), '=' means equals with integers. When you use '=' operator with strings, it performs a shell wildcard pattern matching.

Examples:

{{{
REQUIREMENTS = 'LRMS_TYPE = "pbs"'       # Only use pbs
REQUIREMENTS = 'HOSTNAME = "*.es"'       # Only hosts ending in ".es"
REQUIREMENTS = 'HOSTNAME = "mycomputer"' # Only use mycomputer
REQUIREMENTS = 'ARCH = "x86_64"'         # Only host x86_64 architecture 
REQUIREMENTS = 'ARCH = "x86_64" & HOSTNAME = "*.es"' # Only hosts ending in ".es" and have x86_64 architecture
}}}

You can check the resources that match your requirements with {{{wfr4g_resources -m GW_identification}}}.
{{{
#!sh
[user@mycomputer~]$ wrf4g_status -l
Realization        GW  Stat Chunks Comp.Res   WN         Run.Sta       ext   %
test               0     R  1/3    mycomputer ciclon     WRF            - 0.00
[user@mycomputer~]$ wrf4g_resources -m 0
HID QNAME      RANK  PRI  SLOTS HOSTNAME            
0   default    0     1     0     mycomputer         
}}}

== Requirement Variables ==

If you want to see more information about a single resource, use the {{{wrf4g_resources}}} command followed by the host identification (HID):

{{{
#!sh
[user@mycomputer~]$ wrf4g_resources 
HID PRI  OS              ARCH   NODES(U/F/T)  LRMS         HOSTNAME                      
0   1   GNU/Linux2.6.18 x86_64         0/1/1  FORK         mycomputer                    
[user@mycomputer~]$ wrf4g_resources 0
HID PRI  OS              ARCH   NODES(U/F/T) LRMS         HOSTNAME   QUEUENAME        SL(F/T) WALLT CPUT  COUNT MAXR  MAXQ  STATUS   DISPATCH   PRIORITY                    
0   1   GNU/Linux2.6.18 x86_64        0/1/1  FORK         mycomputer   default           1/1  0     0     0     0     0     NULL     Immediate  NULL    
}}}


The REQUIREMENTS values are: 

||= Variable =||= Description =||
||HOSTNAME||Execution host (e.g. mycomputer)||
||ARCH ||Architecture of the execution host (e.g. i686, x86_64)||
||OS_NAME||Operating System name of the execution host (e.g. Linux, SL)||
||OS_VERSION||Operating System version of the execution host (e.g. 2.6.9-1.66, 3)||
||CPU_MODEL||CPU model of the execution host (e.g. Intel(R) Pentium(R) 4 CPU 2, PIV)||
||CPU_MHZ||CPU speed in MHz of the execution host||
||CPU_FREE||Percentage of free CPU of the execution host||
||NODECOUNT||Total number of cores of the execution host||
||SIZE_MEM_MB||Total memory size in MB of the execution host||
||FREE_MEM_MB||Free memory in MB of the execution hosts||
||SIZE_DISK_MB||Total disk space in MB of the execution hosts||
||FREE_DISK_MB||Free disk space in MB of the execution hosts||
||LRMS_TYPE||Type of local DRM system for execution (e.g. pbs, sge)||
||QUEUE_NAME||Name of the queue (e.g. default, short)||
||QUEUE_NODECOUNT||Total node count of the queue||
||QUEUE_FREENODECOUNT||Free node count of the queue||
||QUEUE_MAXTIME||Maximum wall time of jobs in the queue||
||QUEUE_MAXCPUTIME||Maximum CPU time of jobs in the queue||
||QUEUE_MAXCOUNT||Maximum count of jobs that can be submitted in one request to the queue||
||QUEUE_MAXRUNNINGJOBS||Maximum number of running jobs in the queue||
||QUEUE_MAXJOBSINQUEUE||Maximum number of queued jobs in the queue||
||QUEUE_DISPATCHTYPE||Dispatch type of the queue (e.g. batch, inmediate)||
||QUEUE_PRIORITY||Priority of the queue||
||QUEUE_STATUS||Status of the queue (e.g. active, production)||

== Environment Expression Syntax ==
The syntax of the environment expressions is  specified in a comma-separated, source/destination pair.
{{{
stmt::= VARIABLE = VALUE, VARIABLE = VALUE, ...
}}}

Examples:

{{{
ENVIRONMENT = 'WALLTIME = 00:01:00' # 60 seconds of max walltime
ENVIRONMENT = 'WALLTIME = 00:01:00, MEMORY = 2000' # 60 seconds of max walltime and 2 GB of RAM memory
}}}

== Environment Variables ==
The variables defined in the ENVIRONMENT are:

||=Variable=||=Description=||
||CPUTIME||Maximum amount of CPU time used by all processes in the job ('''HH:MM:SS''')||
||WALLTIME||Maximum amount of real time during which the job can be in the running state ('''HH:MM:SS''')||
||MEMORY||Maximum amount of physical memory used by the job ('''MB''') ||