CFG-08 · Backup & transfer

rsync command builder

Pick the flags you want, see a plain-English explanation of each one, and get the exact command — including the trailing-slash difference that changes what actually gets copied.

Source

Destination

Exclude patterns (comma-separated)

-aArchive mode — preserves permissions, timestamps, symlinks, and recurses into directories. The flag almost every real rsync command starts with. -vVerbose — lists each file as it's transferred, instead of running silently. -zCompress data during transfer. Helps over a slow link; adds CPU overhead for little benefit on a fast local network. -hHuman-readable sizes (1.2M instead of 1234567) in the summary output. --progressShows a live per-file transfer progress bar — useful for large individual files, noisy for many small ones. --deleteRemoves files from the destination that no longer exist in the source — makes the destination a true mirror instead of an accumulate-only copy. See the warning below before enabling this. -nDry run — shows exactly what would happen without changing anything. Always worth one dry run before the first real run of a new command, especially with --delete on. -e sshTransport over SSH — required whenever source or destination includes a user@host: remote path.

--delete deletes. Anything present at the destination but not at the source is removed permanently. Run once with -n (dry run) first and read the output before running for real.

Command

The trailing slash that changes what gets copied

A trailing slash on the source path means "copy the contents of this directory"; no trailing slash means "copy this directory itself, nested one level deeper at the destination." rsync -a ./data/ dest/ and rsync -a ./data dest/ produce genuinely different results — the first copies files directly into dest/, the second creates dest/data/. This is the single most common rsync surprise.

Why a dry run matters more here than almost any other command

-n runs the exact same matching logic as a real transfer and prints what it would do, without touching anything — the closest thing to a safety net rsync has, especially paired with --delete, which is the one flag on this page capable of permanently removing files at the destination.

Further reading: Why Backups Fail When You Need Them Most — the gap between "the backup job ran" and "the backup actually works," and how to close it.

What does the trailing slash on the source actually do?

src/ (with slash) copies the directory's contents into the destination; src (no slash) copies the directory itself as a new subdirectory of the destination. Forgetting this is the most common reason rsync output ends up one level deeper (or shallower) than expected.

Is --delete safe to use?

It's safe when the destination is meant to be an exact mirror of the source and nothing else — run a dry run (-n) first to see exactly what it would remove. It's not safe if the destination has files you've added independently that aren't in the source; those get deleted too.

Do I need -e ssh for a local-to-local copy?

No — only include it when source or destination is a remote user@host:/path location. For two local paths on the same machine, rsync doesn't need SSH at all.

Related tools

DevOps

SSH Config Builder

Build an SSH config file from a form — host aliases, ports, identity files, ProxyJump, and keepalives. No account, nothing leaves your browser.

Open →

DevOps

Cron Expression Builder

Build or decode cron expressions. Enter a cron schedule and get a plain-English description plus the next 10 run times.

Open →

DevOps

systemd Service & Timer Builder

Generate a systemd .service and .timer unit pair from a form — command, user, schedule, and the systemctl commands to enable it. No account, nothing leaves your browser.

Open →

DevOps

chmod & umask Calculator

Convert Linux/Unix file permissions between checkboxes, symbolic notation, and octal — plus a umask calculator showing the resulting default file and directory permissions.

Open →

DevOps

Crontab to systemd Timer Converter

Convert a crontab line into a systemd .service + .timer pair, including the two-OnCalendar-line trick for cron's day-of-month/day-of-week OR behavior. No account, nothing leaves your browser.

Open →

DevOps

Docker Compose Generator

Build a valid Docker Compose file from a form — services, images, ports, volumes, environment variables, and restart policy. No account, nothing leaves your browser.

Open →