aliatx2017/reasonix-hermes/shell-quoting-ssh

Shell Quoting Patterns

When to Use

• Running bash tool with complex commands containing quotes, variables, or special chars
• Executing commands over SSH where quoting nests multiple times
• Debugging shell quoting errors ("unexpected token", "command not found" where it should work)

Fundamental Rules

1. Single quotes — everything literal, no expansion. '$HOME' → literal $HOME
2. Double quotes — variables and $() expand. "$HOME" → /Users/alex
3. No quotes — word splitting + glob expansion. Almost never what you want.

Single Quote Nesting

You CANNOT nest single quotes directly. 'it's' fails. Workarounds:

# End single-quote, insert escaped quote, resume single-quote
echo 'it'"'"'s working'
 
# Or use double quotes (if no $variables to protect)
echo "it's working"
 
# Or use heredoc (best for multi-line)
cat <<'EOF'
it's working
EOF

SSH Quoting — Triple Nesting

SSH adds one level of quoting. Complex commands need careful nesting:

# WRONG — inner quotes break
ssh host "grep 'pattern' file"
 
# RIGHT — outer double, inner single
ssh host "grep 'pattern' file"
 
# HARD — command with both quote types
# Use heredoc to avoid nightmare quoting
ssh host <<'ENDSSH'
  grep "it's done" /var/log/*.log
ENDSSH
 
# OR base64-encode the command
CMD=$(echo 'grep "pattern" file' | base64)
ssh host "echo $CMD | base64 -d | bash"

Common Pitfalls

bash Tool Specific

The bash tool in Reasonix runs commands via a configured shell. Prefer heredocs for multi-line scripts:

cat <<'SCRIPT' > /tmp/script.sh
#!/bin/bash
# complex logic here
SCRIPT
bash /tmp/script.sh

Verification

After any SSH or complex bash command, verify the output is what you expect. A silent success with no output ≠ it worked.

Related

• Project skill: ready-means-tested — verify, don't assume
• Tool: bash — runs commands through configured shell interpreter