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Conor Igoe avatar Ubuntu

Most of the entries in the NAME column of the output from lsof +D /tmp do not begin with /tmp. Why is this the case?

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Conor Igoe

I'm part of a lab that has a shared scientific computing enviornment. My system administrator just told everyone in the lab that one of the nodes I am using is about to crash because /tmp is full. I have been trying to understand how I am using /tmp and am confused. I noticed that running lsof +D /tmp revealed a lot of open files that, according to the entries in the NAME column of the output, did not appear to be in /tmp or any of its subdirectories (and were not listed in the output of ls /tmp) and yet were being included in the command output. For example, here is part of the output:

(base) lsof -u cigoe +d /tmp 2>/dev/null 
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME 
bash 81648 cigoe cwd DIR 253,2 4096 34238020 /home/scratch/cigoe/2022/proposal 
bash 81648 cigoe rtd DIR 253,0 4096 128 / bash 81648 cigoe txt REG 253,0 1150648 3646 /usr/bin/bash 
bash 81648 cigoe mem REG 253,0 2586930 3602 /usr/lib/locale/en_US.utf8/LC_COLLATE 
bash 81648 cigoe mem REG 253,0 9253600 201909537 /var/lib/sss/mc/passwd 
bash 81648 cigoe mem REG 253,0 46320 67889113 /usr/lib64/libnss_sss.so.2 
...

I wasn’t able to get a good understanding of exactly how these open files were being associated with /tmp, but they seemed to collectively take up a lot of space (in terms of the sum of entries in the SIZE/OFF column, far too much to realistically fit on the device, so I’m not sure what’s going on there). In case it's relevant, our lab uses ZFS. I would appreciate help in answering the following question:

Most of the entries in the NAME column of the output from lsof +D /tmp do not begin with /tmp. Why is this the case?

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steeldriver

You are giving lsof two list options, -u cigoe and +d /tmp. From man lsof:

   Normally list options that are specifically stated  are  ORed  -  i.e.,
   specifying  the  -i option without an address and the -ufoo option pro‐
   duces a listing of all network files OR files  belonging  to  processes
   owned by user ``foo''.

so it's returning all the files opened by user cigoe as well as all the open files in /tmp. It goes on to say

   The -a option may be used to AND the selections.  For example, specify‐
   ing -a, -U, and -ufoo produces a listing of only UNIX socket files that
   belong to processes owned by user ``foo''.

So, to list all the files opened by user cigoe AND in (the top level of) /tmp

lsof -u cigoe -a +d /tmp 2>/dev/null
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