SAS Unix Process ID

Today a friend called and wanted to know if there was an easy way to use the Unix Process ID as part of the name of the log file when invoking SAS in batch mode. She wanted to make (semi-)unique log files. She is concerned about uniqueness enough to not want to immediatly overwrite another log file, but not so much that she's worried about possible collisions when the system recycles a process ID.

Well, it just so happens the script variable $$ contains the process ID of that script. So you can use that when constructing your log file name. Such as:

nohup /home/sas mySAScode.sas -log "/tmp/mySAScode_$$.log" &

In the above, nohup tells unix to keep the process alive even after we've closed down our terminal and logged off.
/home/sas is the sas executable (or the script that executes SAS).

An example of the log file created by this command would be /tmp/mySAScode_1298656.log

If you wanted to get the process ID that SAS was started with you can use the automatic macro variable &SYSJOBID within SAS.

If you wanted to learn some more about running SAS on Unix you could also bounce over to SASonUnix.blogspot.com. It has some very good tips.

How To Be Nice

Now that my daughter is mobile, she is constantly interacting with other kids at the park. Being the little social butterfly that she is, she has no problem walking up to other kids and trying to take their toys. Of course, at 15 months old she doesn't really know any better, but I still find myself trailing behind her saying "Be nice. Play nice." Some day soon she might actually listen.

But if you're using batch SAS on Unix, you can be nice today!

The "nice" command is used to raise/lower the priority of your background sas jobs. Generally we all run jobs at the same nice priority, but by lowering your priority you can let your big background jobs run without interfering with other people's jobs. This can be useful during the heavy use times and you are not too concerned about whether your job runs in 30 mins or 60 mins. It essentially lets you get out of the way of other users without putting your jobs on hold. Nice!

Here's how it works. The higher the nice number the lower your priority. The syntax of nice is:
nice -N /your/command/
where N is the number to move your priority. Positive lowers your priority by that amount, negative raises your priority by that amount.

So instead of me running my sas command like this:
$ sas myBigSAS.sas -autoexec "/my/autoexec.sas" &

I can be nice and run it like this:
$ nice -15 sas myBigSAS.sas -autoexec "/my/autoexec.sas" &

That will run my command with a higher nice value (low priority) freeing up resources for other users.