Bash bc and echo commands

Question

I'm writing small geeklet for geektool, to alert me when sum of inactive and free RAM on my Mac will become slow. I'm not really good with bash, so I have a problem with final output (getting blank). Here is code:

inMem=$(top -l 1|awk '/PhysMem/ {print $6}'|sed s/M//) | freeMem=$(top -l 1|awk '/PhysMem/ {print $10}'|sed s/M//) | totalMem=$inMem+$freeMem | bc | echo $totalMem

Also wonder if my issue is optimal or not. Thanks a lot.

Answer 1

I wonder if this could actually simplify your commands. I can't test it since I'm not on OSX but I hope it works.

read inMem freeMem totalMem < <(top -l 1 | awk '/PhysMem/ { i = $6; sub(/M/, "", i); f = $10; sub(/M/, "", f); printf("%d %d %d\n", i, f, i + f); exit; }')
echo "inMem: $inMem"
echo "freeMem: $freeMem"
echo "totalMem: $totalMem"

Answer 2

Instead of parsing top, use the /proc/meminfo file. For example, with:

$ head -2 /proc/meminfo
MemTotal:        4061696 kB
MemFree:          335064 kB

you can see to total and free memory

Answer 3

user000001 answer is right, but then the question is "How to get /proc/meminfo output into variables?"

You can use this pure bash solution for parsing:

read -d '' _  memTotal _ _ memFree _ < <(head -2 /proc/meminfo)