Bash write to file without echo?

bash command-line io-redirection
anon picture anon · Jul 1, 2012 · Viewed 135.6k times · Source

As an exercise, does a method exist to redirect a string to a file without echo? Currently I am using

echo "Hello world" > test.txt

I know about cat and printf. I was thinking something like

> test.txt <<<"Hello world"

Of course this doesnt work, but maybe a similar command?

Answer

Eric picture Eric · Mar 5, 2013

You can do this with "cat" and a here-document.

cat <<EOF > test.txt
some text
EOF

One reason for doing this would be to avoid any possibility of a password being visible in the output of ps. However, in bash and most modern shells, "echo" is a built-in command and it won't show up in ps output, so using something like this is safe (ignoring any issues with storing passwords in files, of course):

echo "$password" > test.txt

Related questions

Capture stdout and stderr into different variables

Is it possible to store or capture stdout and stderr in different variables, without using a temp file? Right now I do this to get stdout in out and stderr in err when running some_command, but I'd like to …

Read More
How do I set a variable to the output of a command in Bash?

I have a pretty simple script that is something like the following: #!/bin/bash VAR1="$1" MOREF='sudo run command against $VAR1 | grep name | cut -c7-' echo $MOREF When I run this script from the command line and pass it …

Read More
How do I parse command line arguments in Bash?

Say, I have a script that gets called with this line: ./myscript -vfd ./foo/bar/someFile -o /fizz/someOtherFile or this one: ./myscript -v -f -d -o /fizz/someOtherFile ./foo/bar/someFile What's the accepted way of parsing this such …

Read More