Extract text from one iteration of top

Question

I want to execute the top command from my bash script

the problem is that usually when I type the top command on the console , I exit by Ctrl+C.

but how to exit from top when I run the top command from my bash script ?

for example how to print the free memory from top in bash ?

I do the following but command not return value as I am explained

 top | grep Mem: | awk '{print $6" "$7}'

when I run the top from the console:

  top

  top - 17:55:24 up 20 days,  8:05,  3 users,  load average: 0.08, 0.08, 0.04
  Tasks:  93 total,   1 running,  92 sleeping,   0 stopped,   0 zombie
  Cpu(s):  1.0%us,  3.2%sy,  0.0%ni, 95.2%id,  0.5%wa,  0.0%hi,  0.0%si,  0.0%st
  Mem:   2075516k total,  1731156k used,   344360k free,   373308k buffers
  Swap:  4192924k total,       76k used,  4192848k free,  1130448k cached

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+       COMMAND                                                               
   1 root      15   0  2072  656  568 S  0.0  0.0   0:01.36 init     
 .
 .
 .

Answer 1

@jimmij's answer is good from the top options point of view, though it looks like the format of the output from top can't be relied upon in a portable manner.

You mention you don't have the free utility, but this is just a wrapper around the /proc/meminfo interface, which you almost certainly do have. Why not just get the information you need directly from the horses mouth (the kernel):

$ grep MemFree: /proc/meminfo
MemFree:           75916 kB
$ 

Or if you want it formatted as a single number by awk:

$ awk '$1=="MemFree:" {print $2}' < /proc/meminfo
74320
$ 

Answer 2

Try this:

top -bn1 | awk '$1=="Mem:" {print $6" "$7}'