How to create simple bar charts in terminal using awk

Today, I tried to visualize how many processes each user is running using simple bar chart. The catch is that I want see results in a plain terminal, which makes things more interesting.

Shell script

I created a simple shell script to count processes per user and print colourful bar chart.

Please notice that I am using GNU Awk 4.0.1
# print "processes per user" bar chart
# source:
# Debian/GNU awk: /usr/bin/awk -> /etc/alternatives/awk -> /usr/bin/gawk

# get usernames
processes=$(ps hax -o user)

# sort and count usernames
user_processes=$(echo "$processes" | sort | uniq -c)

# character used to print bar chart

# current min, max values [from 'ps' output]
vmax=$(echo "$user_processes" | awk 'BEGIN {max=0} {if($1>max) max=$1} END {print max}')

# range of the bar graph

# color steps

# generate output
echo "$user_processes" | awk --assign dmin="$dmin" --assign dmax="$dmax" \
                             --assign vmin="$vmin" --assign vmax="$vmax" \
                             --assign cstep1="$cstep1" --assign cstep2="$cstep2" --assign cstep3="$cstep3" --assign cstepc="$cstepc"\
                             --assign barchr="$barchr" \
                             'BEGIN {printf("%15s %7s %2s%54s\n","username","p-count","|<", "bar chart >|")}
                                printf("%15s %7s ",$2,$1);
                                    if (i >= 1 && i <= int(dmax/3))
                                      {printf(cstep1 barchr cstepc);}
				    else if (i > int(dmax/3) && i <= int(2*dmax/3))
                                      {printf(cstep2 barchr cstepc);}
                                      {printf(cstep3 barchr cstepc);}
                                print ""

The script is self-explanatory, although there is a little math involved to calculate bar width.

Sample output

This is the most interesting part. I should probably put this at the beginning, as one picture is worth more than thousand words.

Ending notes

This idea can be easily expanded further, as you can create graphs for established TCP connections, CPU usage, or anything else you can think of.

Milosz Galazka's Picture

About Milosz Galazka

Milosz is a Linux Foundation Certified Engineer working for a successful Polish company as a system administrator and a long time supporter of Free Software Foundation and Debian operating system.

Gdansk, Poland