Run a shell script only once per time interval

run_per.sh

#!/bin/sh

# Configuration
INTERVAL=10 # (seconds)
LASTRUN=".lastrun" # (optional)

# Run_per logic
NOW=$(date +%s)
test -f "$LASTRUN" && THEN=$(cat "$LASTRUN") || THEN=0
test $INTERVAL -gt $(($NOW - $THEN)) && exit 0
echo -n $NOW > "$LASTRUN"

# Your script below
# ...

run_per_short.sh

#!/bin/sh

# Replace "10" with desired interval in seconds
[ -f .lastrun ]&&[ 10 -gt $((`date +%s`-`cat .lastrun`)) ]&&exit 0||date +%s>.lastrun

# Your script below
# ...