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Control system command directory used (instead of /tmp)
Hi all,
Anyone know if there’s any way to control which directory is used during system commands?
We have run into issues where /tmp is full and would like to use a different directory to avoid processes crashing.
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3 Replies
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You can use named pipes:
Named pipes Knowledge Base kdb+ and q documentation – Kdb+ and q documentation (kx.com) -
We’re not necessarily reading files to use named pipes, even using a grep command still uses the /tmp directory
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You cannot control the use of /tmp but you could possibly use a redirect to send the bulk of output to a different location.
In a basic form:
q)system"ls > /my/chosen/path/out.txt 2>&1;" q)result:read0`:/my/chosen/path/out.txt q)hdel`:/my/chosen/path/out.txt `:/my/chosen/path/out.txt q)result "file1" "file2"
You could aim to make a more reusable function.
For familiarity you could use the TMPDIR environment variable:
q)setenv[`TMPDIR] "/my/chosen/path"
Then create a function to run system commands
systemTMPDIR:{[c] f:first system"mktemp"; //Make a temp file respecting TMPDIR c:c," > ",f," 2>&1;echo $?"; //Add redirect to tmp file and capture of exit code e:"J"$first system c; //Execute the command f:hsym `$f; r:read0 f; //Read the result of the command hdel f; //Delete the tmp file $[not 0=e; //Check if the exit code was an error (not 0) [-1 last r;'`os]; //If an error print the last line and signal with 'os r] //If success return the data }On success:
q)systemTMPDIR"ls" "file1" "file2"
On failure:
q)systemTMPDIR"blah" sh: 1: blah: not found 'os [0] systemTMPDIR"blah" ^
*Note: This is just a small example and likely will not behave the exact same as the native ‘system’ in all cases.
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