Kdb+ minimise use of '/tmp' during 'system' calls

tmp.md

In Kdb+ you cannot control the use of '/tmp' during a system call. You may need to avoid this if the drive space is small.

For familiarity use the TMPDIR environment variable:

q)setenv[`TMPDIR] "/my/chosen/path" 

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.