Monitoring Memory with Swap

A low amount of free memory is an indication that the system has many thing to  do; this may lead to disk swapping. A high use of swap space make a system go slow because disk access is many times slower than access.

cat /usr/local/src/memory.sh
#!/bin/bash
C=$(/usr/bin/free -m| head -2 | tail -n +2 | awk {'print $4'})
C=$(/usr/bin/free -m| head -4 | tail -n +4 | awk {'print $3'})
E=$(date)
printf "%s %s %s %s %s %s\n" "Mem: " "$C" "Swap: " "$D" "At" "$E"

crontab -l
*/5 * * * * /usr/local/src/memory.sh >> /var/log/memory.data

tail -5 /var/log/memory.data
Mem: 76080 Swap: 5274188 At Sat Oct  8 12:44:48 PDT 2016
Mem: 72128 Swap: 5274264 At Sat Oct  8 12:45:01 PDT 2016
Mem: 67780 Swap: 5274428 At Sat Oct  8 12:50:01 PDT 2016
Mem: 68720 Swap: 5274492 At Sat Oct  8 12:55:01 PDT 2016
Mem: 68472 Swap: 5274944 At Sat Oct  8 13:00:01 PDT 2016