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delay execution of a command that needs lots of memory and CPU time until the resources are available

Terminal - delay execution of a command that needs lots of memory and CPU time until the resources are available
( ( while [ 2000 -ge "$(free -m | awk '/buffers.cache:/ {print $4}')" ] || [ $(echo "$(uptime | awk '{print $10}' | sed -e 's/,$//' -e 's/,/./') >= $(grep -c ^processor /proc/cpuinfo)" | bc) -eq 1 ]; do sleep 10; done; my-command > output.txt ) & )
2010-07-13 09:12:11
User: michelsberg
Functions: echo sleep
4
delay execution of a command that needs lots of memory and CPU time until the resources are available

[ 2000 -ge "$(free -m | awk '/buffers.cache:/ {print $4}')" ] returns true if less than 2000 MB of RAM are available, so adjust this number to your needs.

[ $(echo "$(uptime | awk '{print $10}' | sed -e 's/,$//' -e 's/,/./') >= $(grep -c ^processor /proc/cpuinfo)" | bc) -eq 1 ] returns true if the current machine load is at least equal to the number of CPUs.

If either of the tests returns true we wait 10 seconds and check again. If both tests return false, i.e. 2GB are available and machine load falls below number of CPUs, we start our command and save it's output in a text file.

The ( ( ... ) & ) construct lets the command run in background even if we log out. See http://www.commandlinefu.com/commands/view/3115/ .

Alternatives

There are 2 alternatives - vote for the best!

Terminal - Alternatives
echo 'some command' | batch
2010-07-14 03:08:31
User: kniht
Functions: echo
8

If shell escaping of the command is problematic, you can write the command to a file first:

batch <somefile

Or read it:

read -re && echo "$REPLY" | batch

Or, if your shell supports it, you can eliminate echo:

read -re && batch <<<$REPLY

("man batch" lists 1.5 for me, but I don't know how widely it differs.)

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