What is Termchart

Termchart is a simple Python script that takes data from standard input, and draws a barchart on the terminal using ncurses.

Installation

You just need to copy the termchart.py file.

The requirements are:

• Python curses library
• Linux (as the script uses special file like /dev/tty)

Note: this script has not been tested with Python 3

Usage

termchart.py [--no-keep]

The script wait for data coming from standard input. It can be passed using pipes, like cat data.txt | termchart.py.

The script must receive data consisting of numbers, with only one number per line. Everything else will be ignored.

Each time the script receive data, it displays a bar on the terminal with a height relative to the value received. The Y scale is automatically adjusted. If there are more data to display than the width of the terminal, then the data received first is discarded (like a FIFO).

Regarding the --no-keep option, we must consider two cases:

• the stream of data input is finished (example: cat datat.txt | termchart.py)
  • by default, the chart stays on the terminal ; any key will exit
  • with the --no-keep option, the program will exit immediately after the end of the stream, and clear the screen ; so you will not see anything, this option is not useful in that case
• the stream of data is not finished, the chart is updated live, and pressing on CTRL-C will exit the program
  • by default, the chart stays on the terminal ; any key will then exit
  • with the --no-keep option, the program will exit immediately after pressing CTRL-C

Examples

Display user CPU Usage

vmstat 1 | awk '{print $13; fflush(stdout)}' | termchart.py

Note: it is important to use fflush(stdout) in awk to force it to flush immediately.

Ping time

ping www.google.fr | awk 'BEGIN {FS="[=]|[ ]"} NR > 1 {print $11; fflush(stdout)}' | termchart.py

Java Memory Eden space usage

jstat -gc <vmid> 1000 | awk 'NR > 1 { gsub(",", ".", $6); print $6; fflush(stdout); }' | termchart.py