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.

Is there no `free` command in OSX? – Sean Bright Sep 04 '13 at 13:34 — Sean Bright, Sep 04 '13 at 13:34
On OS X, you'd be better off querying `sysctl -a vm` – Michael Foukarakis Sep 04 '13 at 14:01 — Michael Foukarakis, Sep 04 '13 at 14:01

konsolebox · Accepted Answer · 2013-09-04T14:06:34.330

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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"

edited Sep 04 '13 at 14:06

answered Sep 04 '13 at 13:52

konsolebox

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+1 for the general approach, although it could still be simplified a lot if you don't need to have the values in shell variables. – tripleee Sep 04 '13 at 15:49
@tripleee My initial version of it was actually only the command itself without showing the value for `inMem` and `freeMem` but I can't generalize what the OP really wants. – konsolebox Sep 04 '13 at 17:01
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Oh I mean simply `top -l 1 | awk '... END { print "inMem: " i; print "freeMem: " f; print "totalMem: " i+f }'` – tripleee Sep 04 '13 at 18:45
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Thanks a lot) echo commands just for testing, I need only totalMem value, due its show total memory which can be used. – Wiedzmin478 Sep 06 '13 at 15:53

score -1 · Answer 2 · answered Sep 04 '13 at 13:34

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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

answered Sep 04 '13 at 13:34

user000001

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OSX does not have procfs. – Michael Foukarakis Sep 04 '13 at 13:56

score -1 · Answer 3 · edited May 23 '17 at 12:11

-1

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)

edited May 23 '17 at 12:11

Community

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answered Sep 04 '13 at 13:43

Aleks-Daniel Jakimenko-A.

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The only gotcha here is that assuming that the positions map to the desired variables is unsafe without reading their names -- future kernels may reorder while adding new values. – Charles Duffy Sep 04 '13 at 13:54
OS X does not have /proc/meminfo – chepner Sep 04 '13 at 14:59

Bash bc and echo commands

3 Answers3