Learn Rsync - Essential Flags: -a, -v, -h, -z, -P, --delete

#Introduction

So far you've run rsync -avh without really knowing what happens behind each letter. Episode 5 changes that: we dissect one by one the essential flags that will accompany almost every rsync command you write. Mastering the flags means mastering the rsync language — and avoiding surprises like changed permission modes or silently deleted files.

#-a: Archive

-a is the most important flag. It isn't a single behavior, but a combination of several flags at once:

-a = -rlptgoD

With -a, your backup becomes a high-fidelity mirror: files at the destination will have the same permissions, owners, timestamps, and symlinks as the source. That's why -a is called archive mode — it produces a faithful archive copy.

#-v and -h: Verbose and Human-Readable

• -v (verbose) — shows the list of files being transferred. Add more -v (-vv, -vvv) for deeper debug. In production, -v helps you monitor what's actually being done; without -v, rsync is almost silent.
• -h (human-readable) — displays sizes in an easy-to-read format (KB, MB, GB) in the summary output, instead of raw bytes.

rsync -avh src/ dest/

The summary output — sent, received, speedup — is only comfortable to read with -h active.

#-z: Compression

-z compresses data during transfer:

rsync -avhz src/ dest/

-z pays off most on slow or distant networks (WAN, VPN, cross-continent) because it reduces the bytes crossing the connection. Conversely, on fast local networks or disk-to-disk, compression only adds CPU load and can slow things down — and already-compressed files (video, zip, images) can't be compressed further. We'll measure the impact quantitatively in episode 12.

#-P: --partial + --progress

-P is shorthand for two flags at once:

• --partial — keep a file whose transfer was interrupted as a partial file, so it can be resumed, instead of discarding it.
• --progress — show real-time progress: percentage, speed, and estimated time to completion.

rsync -avhP src/ dest/

The -P combination is invaluable for large files (database dumps, images): if the connection drops at 60%, rsync keeps the 60% already done and resumes from there on the next attempt instead of starting from zero. Partial mechanism details are in episode 7.

#--delete: Exact Mirror

--delete makes the destination identical to the source by deleting extra files at the destination:

rsync -avh --delete src/ dest/

Its purpose: keeping a mirror from accumulating files that were already deleted at the source. Without --delete, the destination only grows, never shrinks — over time the backup accumulates garbage that "no longer exists" at the source.

#-n: Dry-Run

-n (dry-run) runs rsync without doing anything — it only shows what would be done:

rsync -avh --delete -n src/ dest/

Dry-run is your number-one safeguard. Combine it with -i (itemize, episode 16) to see the specific changes per file before execution. Production habit: always dry-run first for commands touching important data.

#Common Combinations to Memorize

Starting from these combinations, you just add special flags as needed: filters (episode 6), throttle (episode 12), or checksums (episode 16).

#Closing

In this episode you've mastered the six most important flags in the rsync vocabulary.

Key takeaways:

• -a = -rlptgoD — full fidelity: permissions, timestamps, owner, symlinks, devices.
• -v verbose, -h human-readable, -z compression (a win on WAN, a loss on LAN).
• -P = --partial + --progress — resume interrupted transfers.
• --delete creates an exact mirror; always test with a dry-run first.
• -n dry-run is the number-one safeguard before execution.

In episode 6 we learn to select files: --exclude, --include, --exclude-from, the /dir/ vs dir/ patterns, and a real case of excluding .git/, node_modules, cache, and temporary files from backups. See you in episode 6!