Useful Python one-liners

py-one-liners.sh

# Reading file lines from stdin
cat /tmp/test.txt | python -c 'import fileinput; [print(line, end="" for line in fileinput.input()]
python -c 'import fileinput; [print(line, end="") for line in fileinput.input()]' < /tmp/test.txt

# Printing the 3 lines of the file
python -c "import sys; sys.stdout.write(''.join(sys.stdin.readlines()[:3]))"  < /tmp/test.txt

# Checking if file exists
python -c 'from pathlib import Path; print("yes") if Path("/tmp/metrics.txt").is_file() else print("no")'