I want to save the command line output data in a text file. I am running macOS High Sierra 10.13.6. The problem is, it has some graphical output which I don't want to store. What I need is, only the strings and their corresponding values. Could you help me please?

The shell command I am running is:

pwmetrics http://www.cnn.com --runs=1

And the output shown in the Terminal is:

enter image description here

This tool to generate web page performance metrics is open source. Here is the error I am getting while I try to save my code:

the error

And the o.txt file contains nothing.

The shell command I have tried so far are:

pwmetrics http://www.ieee.org --runs=2 &> /Users/ssr/Desktop/o.txt
pwmetrics http://www.ieee.org 2>/dev/null | tee /Users/ssr/Desktop/o.txt
pwmetrics http://www.ieee.org yes>/dev/null | tee /Users/ssr/Desktop/o.txt
  • Great question. Since it’s open source, there are easy ways to figure out these are ANSI escape sequences and quite a few options to quash them. Hopefully my answer gives you some direction or ideas to try. Especially the quick one of set term dumb and rerunning the command one time.
    – bmike
    Sep 11, 2018 at 4:19

1 Answer 1


You’ve got several options with that tool.

  1. Output JSON and parse that
  2. Upload to Google Sheets and export as CSV the text you need
  3. Use a tool to strip the ANSI escape codes that prettify (in the opinion of some) and color the text - one package to strip ANSI is https://github.com/chalk/strip-ansi
  4. Use other tools to strip these out by piping the output or saving it to a file - https://unix.stackexchange.com/questions/4527/program-that-passes-stdin-to-stdout-with-color-codes-stripped or https://superuser.com/questions/380772/removing-ansi-color-codes-from-text-stream
  5. Trying to set your terminal type to TERM=dumb (like Can't plot with gnuplot on my Mac)
  6. forking that project and changing the code so the ANSI escape values are nothing. (Lines 4-8 here https://github.com/paulirish/pwmetrics/blob/master/lib/utils/messages.ts or perhaps a few lines down where those variables are used to construct the output)

I would also tell the program to write your output file so you get a clearer view without needing to debug file handling and pipes in bash (assuming that’s not your strength here today).

  • 1
    Thank you so much @bmike, it was a helpful explanation!
    – temp
    Sep 25, 2018 at 2:12

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