First write hello, world into /tmp/a.txt:
hello, world
/tmp/a.txt
echo "hello, world" > /tmp/a.txt{{execute T2}}
echo "hello, world" > /tmp/a.txt
Use cat to concatenate and print files, which is pretty much alike in linux.
cat
cat /tmp/a.txt{{execute T2}}
cat /tmp/a.txt
Then you can see that hello, world has been printed out.