Mac OS X Mavericks and Yosemite running out of memory "fix"

Silly Mac OSX.

Clean up memory cache easily this way:

Add the following entry in your root's crontab:
# Clean up memory
30 * * * * /usr/sbin/purge &

Use at your own risk, but I have not had issues with it.

If you don't know how to update your root crontab, well, then you have no business running this. Use some 3rd party graphical app or something to clean up.

FYI: Some people are having issue with Chrome and Flash and other programs not "letting go" of reserved memory, after use. This will help alleviate the issue. Developers are arguing over it's use, claiming memory management is just fine in OS X 10 Mavericks and later. I beg to differ as I have seen memory run out several times myself with using Chrome web browser and it not letting resources go.

You can read more about it, here:
http://osxdaily.com/2013/11/14/use-purge-command-os-x-mavericks/

Recover a file with LSOF....

Just a quick and dirty of how to recover a file in LSOF.

lsof (List Open Files) is a *nix tool that will show open files and network connections. Of course, it's also available for OS X.

You can recover deleted files with it.

If you have ever deleted a file by mistake you can recover the deleted file. 

For example, to recover a missing messages log used by Syslog you can search for it via this command:

bash:~  lsof | grep messages

You should see something similar to:

syslogd   15328      root    2w      REG              253,2   1419873               983175 /var/log/messages.5 (deleted)

You want to find what is marked as deleted in parenthesis.  The process (15328) still has the file open. Without this process keeping the file open we would have lost the file permanently. This is important. Once the process stops, you won't be able to trace the file this way, so avoid rebooting or stopping the process entirely, until after you've recovered the lost file.

We can view the missing info by looking inside the proc filesystem, the process id (15328), and in the file descriptor (fd). The fd is found in the 4th entry, above (2w in this example):

bash:~  cat /proc/15328/fd/2

This outputs the contents the deleted messages.5 file. As you can see, the data is still there. Now, just redirect the contents back to /var/log/messages.5:

bash:~  cat /proc/15328/fd/2 > /var/log/messages.5

That's all there is to it. You have recovered the file with all the data back to its original location. You should also restart the process, writing to the file(s) recovered.

This is just one of many examples of how lsof can be very useful. Be sure to check out the Man pages and other docs.