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+# impatient
+
+A general purpose utility for estimating when a task will complete
+
+## Overview
+
+`impatient` is sort of like `pv` for tasks where you can't insert
+extra commands into a pipeline, and sort of like `progress` for tasks
+that aren't reading/writing a specific file on the local system.  If
+you give it any shell command that outputs a number (possibly with a
+K/M/G/T suffix), it will repeatedly run the command and show you how
+fast that number is changing.  If you give it the expected final value
+of the number, it'll also estimate how much longer you have to wait.
+It also has a specific option for tracking the total size of a
+file or directory as given by `du`.
+
+For example, here's `impatient` tracking an in-progress `zfs send` to
+a remote machine:
+
+```
+$ impatient -f "$(zfs list -pH -o used pool/home)" -c 'ssh remote-server zfs list -pH -o used remote-pool/backups/pool/home' -i 60
+109.8G - 2.8M/s - 263.7G total - 41.6% complete - 15h03m remaining - ETA 2021-11-23 11:34
+```
+
+Note that `-f` is given the value output by `zfs list`; we could
+give it a number directly, this just simplifies things in this
+particular scenario.  The `-p` flag for `zfs list` isn't strictly
+necessary, `impatient` can parse values like `50.7G`, but
+using the exact byte value provides more precision.
+
+`-c`, on the other hand, is given a quoted string containing a
+command, which will output the current progress value each time it's
+run. The command given to `-c` can be an arbitrary shell one-liner,
+use responsibly.
+
+## Usage
+
+```
+usage: impatient [-h] [-f FINAL] [-i INTERVAL] [-w WINDOW] (-p PATH | -c COMMAND)
+
+Display progress and time estimates for arbitrary tasks
+
+optional arguments:
+  -h, --help            show this help message and exit
+  -f FINAL, --final FINAL
+                        Expected final size/value at completion, optionally with a K/M/G/T suffix
+  -i INTERVAL, --interval INTERVAL
+                        Interval in seconds between samples (default 10)
+  -w WINDOW, --window WINDOW
+                        Number of samples to keep for the sliding window (default 100)
+  -p PATH, --path PATH  Track total disk usage of a given path
+  -c COMMAND, --command COMMAND
+                        Track value returned by a shell command; this should return a single number, optionally with a K/M/G/T suffix
+```