Master Automatic SSH Login on macOS with iTerm2 Triggers, Expect, and Zmodem

1. Automatic login via iTerm2 Triggers

iTerm2 provides a powerful Trigger feature that runs actions when terminal output matches a regular expression. By creating a trigger that detects the password prompt, you can configure the Command field of a profile with the target ssh address, enable Instant, and set the action to Send Text with your password followed by \r. Adjust the regex (e.g., (p|P)ass(word|wd):) to match different password prompts and avoid accidental matches.

After configuring the trigger, you can double‑tap the trackpad or right‑click to select the profile and log in automatically. Note that triggers fire for any matching text, so refine the regex to prevent unintended password entry when chaining SSH sessions.

2. Automatic login via Expect

Expect automates interactive programs. Create a script /usr/local/bin/iterm2Login.sh:

#!/usr/bin/expect
set timeout 30
set host [lindex $argv 0]
set port [lindex $argv 1]
set user [lindex $argv 2]
set pswd [lindex $argv 3]
spawn ssh -p $port $user@$host
expect {
    "(yes/no)?" {send "yes
"; exp_continue}
    -re "(p|P)ass(word|wd):" {send "$pswd
"}
}
interact

Make it executable ( sudo chmod +x /usr/local/bin/iterm2Login.sh) and replace the profile’s Command with a call to this script, passing host, port, user, and password. This method isolates each login, avoiding the trigger‑related password‑leak issue when hopping between servers.

3. Fast file transfer with Zmodem

Install lrzsz on both server and macOS client ( apt-get install lrzsz or yum install lrzsz, brew install lrzsz). Add two iTerm2 triggers: one for rz (receive) and one for sz (send), each running the provided iterm2-zmodem.sh script from GitHub .

To send a file, run rz on the remote host; iTerm2 will prompt you to select a local file. To receive, run sz filename on the remote host; iTerm2 will ask where to save the file. Combine with Expect for fully automated transfers.

4. Summary

This guide shows how to use iTerm2 Triggers, Expect scripts, and Zmodem to achieve password‑less SSH login and rapid file transfer on macOS. The Trigger method works for single hops, while Expect provides a reusable solution for multiple servers. Adding Zmodem support completes the workflow, and the article also addresses common issues such as locale settings and regex conflicts.