echo command: print text and variable values

Syntax

echo [options] string...

It prints the strings you pass, followed by a single newline.

Try it first

$ echo hello world
hello world

Arguments are split on spaces and printed back joined by one space each. That is why extra spaces collapse.

$ echo hello    world
hello world

Quote the text to keep it exactly as written.

$ echo "hello    world"
hello    world

Looking inside a variable

With $, the shell replaces the name with its value before echo ever sees it.

$ echo $HOME
/home/user
$ echo $PATH
/usr/bin:/bin:/usr/local/bin

This is the everyday use. It lets you confirm that a value you thought you set is really there, before you run the thing that depends on it.

Choosing your quotes

Inside double quotes a variable turns into its value. Inside single quotes it does not.

$ echo "deployed by $USER"
deployed by user
$ echo 'deployed by $USER'
deployed by $USER

Use single quotes when you want to show the $ text itself.

Writing to a file

> sends the text to a file instead of the screen.

$ echo build ok > result.txt
$ cat result.txt
build ok

>> adds to the end.

$ echo second line >> result.txt
$ cat result.txt
build ok
second line

> overwrites. Point it at the same file again and whatever was there is gone.

$ echo overwritten > result.txt
$ cat result.txt
overwritten

Tabs, newlines and no newline

-e makes escapes such as \t and \n mean tab and newline.

$ echo -e "name\tstatus"
name	status

-n leaves off the final newline.

$ echo -n done
done

When you actually reach for it

echo is what you type to check something and to add a single line.

Things that trip people up

> overwrites. Typing > when you meant to add a line to .gitignore or .env throws away the rest of the file. Adding is always >>.

A misspelled variable is not an error.

$ echo $NOPE

$ echo "[$NOPE]"
[]

A name that does not exist expands to nothing at all. Wrap it in brackets and you can see whether it is empty.

The shell expands *, not echo.

$ echo *.txt
notes.txt result.txt

echo never sees *.txt. The shell replaces it with the matching file names first, and hands the result over. That order is exactly why echo *.txt is worth typing before rm *.txt.

Do not echo secrets. They stay on the screen and in your shell history. If you only need to know whether a value is set, printing [$TOKEN] to see that it is not empty is enough.