By Mark Paget
[problem]
You want to resize images from the command line.
[/problem]
[solution]
Use image magik mogrify command.
mogrify -resize "percentage" image_na
Also you can view current sizing – like this:
% identify IMG_3864.JPG
IMG_3864.JPG JPEG 563x422 563x422+0+0 DirectClass 8-bit 32.8887kb
[/solution]
[example]
mogrify -resize 20% IMG_3705.JPG
[/example]
[reference]
[tags]mogrify[/tags]
[/reference]
[problem]
You want to listen on a pipe and perform commands, based on the text sent to the pipe.
This could be useful for triggering action based on events;
Running code as different users – i.e. allow root or a functional user to run something – just need to allow access to group of users, via permission to write to the pipe.
[/problem]
[solution]
1. mknod /tmp/.restart_crd
2. chmod a+w /tmp/.restart_crd
3. nohup tail -f /tmp/.restart_crd| while read line
do
case "$line" in
'restart') cmd="./stop >> /tmp/restart.log 2>&1; sleep 5; ./start >> /tmp/restart.log 2>&1";;
'stop') cmd="./stop >> /tmp/restart.log 2>&1";;
'start') cmd="./start >> /tmp/restart.log 2>&1";;
*) cmd="no match ${line}.";;
esac
echo "command is $cmd"
eval $cmd
sleep 5
done &
4. disown
[/solution]
[example]
$ echo "restart" > /tmp/.restart_crd
$ echo "start" > /tmp/.restart_crd
$ echo "stop" > /tmp/.restart_crd
Watch output in by tail -f /tmp/restart.log
[/example]
[reference]
[tags], Unix Coding School[/tags]
[/reference]