Why I Use Printf Over Echo

Stephen SooHoo — Sat, 04 Dec 2021 04:44:54 +0000

This post originally appeared on my personal blog.

While echo is the more widely known command for printing text to standard out, I have found behavior and documentation inconsistencies in its varying implementations¹.

macOS echo man page:

Ubuntu echo man page:

In addition, it's default behavior can cause unintended results when combined with character sensitive commands like base64. Here are a few use cases where echo has caused some trouble for me.

Base64 encoding credentials to put into secret management (Hashicorp Vault, kubernetes, etc.)
```
#!/usr/bin/env bash

PASSWORD="supersecretpassword"

# echo output
echo "${PASSWORD}" | base64
c3VwZXJzZWNyZXRwYXNzd29yZAo=

# printf output
printf "${PASSWORD}" | base64
c3VwZXJzZWNyZXRwYXNzd29yZA==
```
Echo appends a newline to the end of your output which will be passed in the output piped to the base64 command and also appear in the base64 encoded output.

Doing script output

Desired output

one line
two line
three line
four

Script

#!/usr/bin/env bash

INPUT="one line\ntwo line\nthree line\nfour"

# echo output
echo "${INPUT}"
one line\ntwo line\nthree line\nfour

# printf output
printf "${INPUT}"
one line
two line
three line
four

The desired output can be achieved using echo with the -e argument, but as shown in the screenshots above, it's not always documented.

https://unix.stackexchange.com/a/65819 ↩

DEV Community: Stephen SooHoo

Why I Use Printf Over Echo