First Grep

Download it:

curl -s https://jupiter.challenges.picoctf.org/static/515f19f3612bfd97cd3f0c0ba32bd864/file -o file

We can try to read that file with cat:

cat file

Because the file is not very big we can see the flag directly, but also we can use grep which is a command line that helps us to get some string or regex from a file:

cat file | grep 'picoCTF{.*?}'

We solved it.