Carriage return with echo command

Question

I was practicing echo command with option \r (carriage return) as below.

echo -e "This is \r my college"

output:

 my college

but when I add one more word before \r as below

echo -e "This is the \r my college"

Then it gives me output like:

 my college the

Another example

echo -e "This is \r valid data"
 valid data

echo -e "This is not a \r valid data"
 valid data a

So, I wanted to know that what is the actual purpose of carriage return here?

Solution

The \r is just that, a "carriage return" - nothing else. This means what is after the \r will overwrite the beginning of what has already been printed.

For example:

echo -e "1234\r56"

Will display:

5634

echo has printed 1234 then gone back to the begining of the line and printed 56 over the top of 12.

For a new line, try \n instead. No need for spaces too. For example:

echo -e "This is\nmy college"

Which will output:

This is
my college

The carriage return is useful for things like this:

#!/bin/sh
i=0
while [ $i -lt 3 ]
do
    echo -ne "\r"`date` #you should remove new line too
    sleep 1
    i=$(($i + 1))
done
exit

Which will display date over the top of itself instead of creating a new line after each loop.

Comments

[Kusalananda]

This is not reproducible. The second command results in the output ␣my college, just like the first one.

[tripleee]

echo -e is notoriously unportable. You shoud probably use printf instead.

[George Vasiliou]

Related : unix.stackexchange.com/questions/355559/…

[Trevor Boyd Smith]

carriage return is also used in the sysvinit provided functions. For example the function echo_success from /etc/init.d/functions.