in reply to Simultaneously process the multiple files at the same time

Does your conversion processing take substantially longer than running the command:

cat *.csv > /dev/null

[download]

If so, there may be some scope for improvement.

But (as pointed out by everyone else) you are going to have to supply more information. Including the size of the files; how long it currently takes; how you are performing the conversion (the code!); what hardware you are running on; can you put the output files on a different drive to the input files. Etc.

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