Bash Scripting: echo not supporting end-of-options

[kayvortex]

I've built a simple bash shell script, but at some point I need to do a:

var1="$(echo "$var2" | sed fairly_complex_substitute_expr -)"

So, I need to make sure echo will actually echo var2 (which could be anything). However, since bash's echo (and also /bin/echo) does not recognize "--" as an end-of-options option, I'm pretty much stuck if var2 is "-e" or "-n" or "-E", right?

Does anybody know of a way to make bash's echo print out "-n", for example. Id est, does anyone know how to make the following work:

echo '-n' '-e' '-E' # does not echo "-n", "-e", or "-E"

I could, of course, use printf:

printf -- "-n\n"
which works OK; or put a character in and then cut it:

var="_$var" && echo "$var" | cut -c 2-
or use awk:

echo | awk '{ print substr("'"$var"'",1) }'
but this seems like a pointless complication when

echo -- -n
would have been so much simpler! (Zsh's echo allows me to use "-" to signify the end of options; although why it's not "--" I don't know.)

If I am genuinely stuck with the more convoluted methods, does anyone at least know why this behaviour is not implemented?

[croto]

if you don't mind an extra space, you could do something like


echo '' '-n' '-e' '-E'

It looks like an argument not recognized as an option serves as an end-of-option flag...

[geirha]

Use here-string (assuming you are scripting in bash)

sed ... <<< "$var"
printf should also be safe

printf "%s" "$var" | sed ...
Though with the here-string, you don't get the overhead of a pipe, so it should be more efficient.

[kayvortex]

croto:
I'd have to cut the space from the output, but yes that's a workaround I considered.

geirha:
Thanks, that's even better than echoing and piping. (Yes, I'm scripting in bash; and also zsh too actually, and zsh can use the here-string as well.)

I'll take the lack of responses on echo itself as tacit confirmation that there's no direct way for bash's echo to print strings identical to its accepted options. However, there are enough workarounds here for me to mark the thread as solved. Thanks for the help.