How can I execute local script on remote machine and include arguments?

Question

I have written a script that runs fine when executed locally:

./sysMole -time Aug 18 18

The arguments "-time", "Aug", "18", and "18" are successfully passed on to the script.

Now, this script is designed to be executed on a remote machine but, from a local directory on the local machine. Example:

ssh root@remoteServer "bash -s" < /var/www/html/ops1/sysMole

That also works fine. But the problem arises when I try to include those aforementioned arguments (-time Aug 18 18), for example:

ssh root@remoteServer "bash -s" < /var/www/html/ops1/sysMole -time Aug 18 18

After running that script I get the following error:

bash: cannot set terminal process group (-1): Invalid argument
bash: no job control in this shell

Please tell me what I'm doing wrong, this greatly frustrating.

Answer 1

You were pretty close with your example. It works just fine when you use it with arguments such as these.

Sample script:

$ more ex.bash 
#!/bin/bash

echo $1 $2

Example that works:

$ ssh serverA "bash -s" < ./ex.bash "hi" "bye"
hi bye

But it fails for these types of arguments:

$ ssh serverA "bash -s" < ./ex.bash "--time" "bye"
bash: --: invalid option
...

What's going on?

The problem you're encountering is that the argument, -time, or --time in my example, is being interpreted as a switch to bash -s. You can pacify bash by terminating it from taking any of the remaining command line arguments for itself using the -- argument.

Like this:

$ ssh root@remoteServer "bash -s" -- < /var/www/html/ops1/sysMole -time Aug 18 18

Examples

#1:

$ ssh serverA "bash -s" -- < ./ex.bash "-time" "bye"
-time bye

#2:

$ ssh serverA "bash -s" -- < ./ex.bash "--time" "bye"
--time bye

#3:

$ ssh serverA "bash -s" -- < ./ex.bash --time "bye"
--time bye

#4:

$ ssh  < ./ex.bash serverA "bash -s -- --time bye"
--time bye

NOTE: Just to make it clear that wherever the redirection appears on the command line makes no difference, because ssh calls a remote shell with the concatenation of its arguments anyway, quoting doesn't make much difference, except when you need quoting on the remote shell like in example #4:

$ ssh  < ./ex.bash serverA "bash -s -- '<--time bye>' '<end>'"
<--time bye> <end>

Answer 2

On Handling Arbitrary Arguments

If you're really only using a single string, ie. -time Aug 18 18, then you can simply hardcode it, and existing answers tell you how to do that adequately. On the other hand, if you need to pass unknown arguments through (like a message to be displayed on the other system, or the name of a file created where end-users could control its name), then more care is needed.

---

With bash or ksh as /bin/sh

If your remote /bin/sh is provided by bash or ksh, you can safely do the following with an untrusted argument list, such that even malicious names (like $(rm -rf $HOME).txt) can be passed as arguments safely:

runRemote() {
  local args script

  script=$1; shift

  # generate eval-safe quoted version of current argument list
  printf -v args '%q ' "$@"

  # pass that through on the command line to bash -s
  # note that $args is parsed remotely by /bin/sh, not by bash!
  ssh user@remote-addr "bash -s -- $args" < "$script"
}

---

With Any POSIX-Compliant /bin/sh

To be safe against sufficiently malicious argument data (attempting to take advantage of the non-POSIX compliant quoting used by printf %q in bash when nonprintable characters are present in the string being escaped) even with a /bin/sh that is baseline-POSIX (such as dash or ash), it gets a bit more interesting:

runRemote() {
  local script=$1; shift
  local args
  printf -v args '%q ' "$@"
  ssh user@remote-addr "bash -s" <<EOF

  # pass quoted arguments through for parsing by remote bash
  set -- $args

  # substitute literal script text into heredoc
  $(< "$script")

EOF
}

---

Usage (for either of the above)

The functions given above can then be invoked as:

# if your time should be three arguments
runRemote /var/www/html/ops1/sysMole -time Aug 18 18

...or...

# if your time should be one string
runRemote /var/www/html/ops1/sysMole -time "Aug 18 18"

Answer 3

Enclose the command(s) in quotes as follows:

ssh myserver "date +\"Date: %Y%m%d %H:%M\";printf \"Uptime: \";uptime;printf \"uname: \";uname -a"
Date: 20200409 20:02
Uptime:  20:02:29 up 66 days, 55 min,  2 users,  load average: 0.06, 0.05, 0.08
uname: Linux zltcmtn23aecc1rx7322 4.4.0-116-generic #140-Ubuntu SMP Mon Feb 12 21:23:04 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux
Connection to 105.31.182.217 closed.

Answer 4

say a.a is a local file that contains ls

$ssh servername "cat | bash" < a.a

change 127.0.0.1 to whatever your remote ip is

these two give a message about pseudo tty allocation but they work.

$ cat a.a | ssh 127.0.0.1

$ ssh 127.0.0.1 <a.a

Or

$ cat a.a | ssh 127.0.0.1 bash or

$ ssh 127.0.0.1 bash < a.a