Linux命令替换$（cat…）混乱

Question

I am configuring NPM to use TLS (this is unrelated). I have some confusion with how the command substitution in BASH works..

I am issuing the following commands npm config set cert "$(cat public.pem)"

This command works as intended setting the cert field in my .npmrc to the contents of public.pem

Next I issue the command npm config set key "$(cat private.pem)"

This command fails silently and sets the key field in my .npmrc to empty.

It seems the private key file starts with the standard -----BEGIN RSA PRIVATE KEY----- and my public key starts with Bag Attributes. It seems the file starting with dashes is messing up my command substitution.

Thoughts?

Answer 1

Where did the cat go in the failing command?

npm config set key "$(cat private.pem)"

Note that you can also use

$(< private.pem)

which should be a bit faster than calling cat .

Answer 2

After a little more research this isn't a problem with command substitution. npm config set.... seems to ignore input that starts with dashes.

npm config set key ---- fails whereas npm config set key 1234 works