通过SSH运行多行bash命令不起作用

Question

I need to run a multi-line bash command over ssh, all possible attempt exhausted but no luck --

echo "3. All files found, creating remote directory on the server."
ssh -t $id@$host bash -c "'
                if [[ -d ~/_tmp ]]; then
                    rm -rf ~/_tmp/*
                else
                    mkdir ~/_tmp
                fi
'" ;

echo "4. Sending files ..."
scp ${files[@]} $id@$host:~/_tmp/ ; 

Here is the output --

user@linux:/tmp$ ./remotecompile
1. Please enter your id:
user
2. Please enter the names of the files that you want to compile
   (Filenames *must* be space separated):
test.txt
3. All files found, creating remote directory on the server.
Password: 
Unmatched '.
Unmatched '.
Connection to host.domain.com closed.

Please note, I do not want to put every 2-3 lines of bash if-then-else-fi commands into separate files.

What is the right way to do it?

Answer 1

Use an escaped heredoc to have its literal contents passed through. (Without the escaping, ie. using just <<EOF , shell expansions would be processed locally -- making for more interesting corner cases if you used variables inside your remotely-run code).

ssh "$id@$host" bash <<'EOF'
if [[ -d ~/_tmp ]]; then
    rm -rf ~/_tmp/*
else
    mkdir ~/_tmp
fi
EOF

If you want to pass arguments, doing so in an unambiguously correct manner gets more interesting (since there are two separate layers of shell parsing involved), but the printf '%q' builtin saves the day:

args=( "this is" "an array" "of things to pass" \
       "this next one is a literal asterisk" '*' )
printf -v args_str '%q ' "${args[@]}"
ssh "$id@$host" bash -s "$args_str" <<'EOF'
  echo "Demonstrating local argument processing:"
  printf '%q\n' "$@"
  echo "The asterisk is $5"
EOF

Answer 2

This works for me:

ssh [hostname] '       
if [[ -d ~/_tmp ]]; then
   rm -rf ~/_tmp
else
   mkdir ~/_tmp
fi
'