This isn't a question of printf vs echo.
I'm trying to edit my script to use printf exclusively, and I have the following in my code:
echo >&2 'Failed to initialize REPL repo. Please report this!'
If I replace echo with printf, will it introduce any side effects (because of the >&2)?
printf >&2 'Failed to initialize REPL repo. Please report this!\n'
I couldn't find an answer in askubuntu. Either there isn't one or the search is ignoring the > and & characters.
A redirection like >&2 is a feature of the shell running your script, the program whose output gets redirected is not relevant for it. Yes, if you only ask about the redirection, that’s the same – you don’t have to worry about it unless you change the shell. See your shell‘s manual for details about this feature, e.g. man bash/REDIRECTION for bash.
There’s a nice answer about the differences between echo and printf over on Unix & Linux: Why is printf better than echo?
As for why you can’t search for symbols on AU, see this meta Q&A: How to search AU for a string containing “$”?
If I replace echo with printf, will it introduce any side effects (because of the >&2)?
The >&2 part has nothing to do with either echo nor printf. The >& is a shell redirection operator, where in this case it duplicates stdout (implied, though could be referenced explicitly with 1>&2) of the command to stderr ( file descriptor 2). They can appear in any order in a command in bourne-like shells. The only issue that can happen is with csh shell and its derivatives(see related post). So, so long as you are using bourne-like shells ( dash, bash, ksh ) you should be fine.
As for printf vs echo generally printf is preferred because it's more portable. See Why is printf better than echo?
