Put a condition inside a cat in bash

Question

I am relatively new with bash and I wonder if it is possible to put a condition inside a cat in bash

cat > /root/file <<EOL
A line of text
Some other text
EOL

Now i want to put an if condition inside the cat command.For e.g if [condition] = something then Some other text is written to file.

Thanks in advance......

Answer 1

Not with cat specifically. But you don't have to write everything at once; use append redirection operator >>.

echo "A line of text" > /root/file
if [ "$FOO" = bar ]
  echo "Another line of text" >> /root/file
fi

Or equivalently with cat:

cat > /root/file <<EOL
A line of text
EOL
if [ "$FOO" = bar ]
  cat >> /root/file <<EOL
Another line of text
EOL
fi

Answer 2

No. cat is not a programming language, and bash is not responsible for interpreting (most of) the data sent to it. Consider using something like awk instead.