Run a command without PTY

Question

I am writing a test script and need to gather "free -m" output at some interval at background. However, watch cmd sends control sequences to delete old output, thinking it is in a terminal. But I don't want that, I want the values throught the process. Is this possible?

In short; I run

watch -n 1 "free -m | grep buffers/cache" > time

And I expect time to have multiple lines of:

-/+ buffers/cache: 2212 5730 -/+ buffers/cache: 2219 5730 -/+ buffers/cache: 2217 5730

However it only contains:

0u May 8 20:39:19 2014 -/+ buffers/cache: 2212 5730

Answer 1

Just use a loop:

while : ; do free -m | grep buffers; sleep 1; done

The colon is equivalent to true.

Redirect to a file called time if you like:

while : ; do free -m | grep buffers >> time; sleep 1; done