This page describes how to convert text from the command line to a pdf in linux. It uses the text2pdf.

Download the source:

mkdir -p $HOME/devel/text2pdf/source
cd $HOME/devel/text2pdf/source
wget http://www.eprg.org/pdfcorner/text2pdf/text2pdf.c

Then add the following line in the code after the last #define

using namespace std;

Also comment out the minimum page dimension condition in line 426 and 430. It should show:

...
// if (pageWidth < 72) pageWidth = 72;
...
// if (pageHeight < 72) pageHeight = 72;
...

To adapt the placing of the text to the upper left corner, modify line 199 into the following:

sprintf(buf, "1 0 0 1 5 %d Tm\n", pageHeight - 10); writestr(buf);

While ignoring all warnings, build from source with:

g++ text2pdf.c -fpermissive -o text2pdf

See options with this command:

./text2pdf -h

And test with:

./text2pdf -fCourier-Bold -s30 -x100 -y30 > out.pdf <<< "20001"
xdg-open out.pdf