与 ssh 一起使用时忽略 sh 命令的 Arguments

Question

In the following command, the first argument of sh command echo hey is ignored:

$ ssh localhost sh -c 'echo hey; echo ho'

ho

Why?

Answer 1

Your commandline is:

ssh localhost sh -c 'echo hey; echo ho'

ssh starts a shell on localhost and passes it the comandline:

sh -c echo hey; echo ho

The shell on localhost sees two commands. Both run fine.

The problem is that the first command is: sh -c echo hey

The option -c tells sh to execute the next argument. The next argument is echo . The extraneous hey argument is ignored.

To fix your problem, either change your quoting or just don't run the redundant shell:

ssh localhost "sh -c 'echo hey; echo ho'"

ssh localhost 'echo hey; echo ho'

The main confusion is probably that ssh concatenates all the non-option arguments it receives into a single string that it passes to the remote shell to execute.