From f90398182f63e9acbfbb39c252fe900ac395006d Mon Sep 17 00:00:00 2001 From: sneak Date: Wed, 11 Nov 2026 03:54:15 +0000 Subject: [PATCH] README: guard the daily cron scan against an unmounted disk (closes #175) A disk that is not mounted leaves its mount point an empty directory. scan then deletes every record under it, and the next scan reads every file again. The README now says so. Its cron line runs scan only when mountpoint finds the disks mounted, and one sentence says which mount points to test. The Description drops its sentence on copies deleted after the scan: "Reading the reports" and "Goals" already say it. Model: opus-5-5 --- README.md | 18 +++++++++++------- TODO.md | 3 +++ 2 files changed, 14 insertions(+), 7 deletions(-) diff --git a/README.md b/README.md index f70186e..e1b6fc3 100644 --- a/README.md +++ b/README.md @@ -22,9 +22,8 @@ records the files it finds in an SQLite database. SQLite keeps a whole database in one file. The database is kept between runs. A rescan reads only new and changed files. That makes `scan` cheap enough to run every day from `cron`, the system's job scheduler. `report`, `trees` and `info` work from the database and -can run at any time. `report` and `trees` leave out a copy that was deleted -after the scan. `dwim` scans `/` and then prints the `trees` report, for a first -look at a new machine with one command. +can run at any time. `dwim` scans `/` and then prints the `trees` report, for a +first look at a new machine with one command. ## Getting Started @@ -115,15 +114,20 @@ docker run --rm -v /srv:/srv:ro -v /var/lib/sfdupes:/var/lib/sfdupes \ Run `scan` as root, so that it can read every file. `scan` warns about a directory it cannot read, and about a new or changed file it cannot read. It skips the path and deletes the records at or below it (see "Rules for the -walk"). As the file `/etc/cron.d/sfdupes`: +walk"). + +An unmounted disk leaves its mount point empty, so `scan` deletes every record +under it, and the next scan reads every file on the disk again. Test the mount +point of each disk at or below `/srv` with its own `mountpoint -q`, joined with +`&&`, and test `/srv` only when it is one. As the file `/etc/cron.d/sfdupes`: ``` -30 3 * * * root /usr/local/bin/sfdupes scan /srv 2>>/var/log/sfdupes.log || tail -n 3 /var/log/sfdupes.log +30 3 * * * root if mountpoint -q /srv; then /usr/local/bin/sfdupes scan /srv 2>>/var/log/sfdupes.log || tail -n 3 /var/log/sfdupes.log; else echo "a disk is not mounted; scan of /srv skipped"; fi ``` - The first scan creates `/var/lib/sfdupes/db.sqlite` and its directory. To keep - the database elsewhere, put `SFDUPES_DATABASE=/path/to/db.sqlite` before the - command on the same line. + the database elsewhere, put `SFDUPES_DATABASE=/path/to/db.sqlite` directly + before `/usr/local/bin/sfdupes`. - `scan` writes nothing to stdout. Its stderr, appended here to `/var/log/sfdupes.log`, holds: - one line naming the database; diff --git a/TODO.md b/TODO.md index b98640a..d7028b7 100644 --- a/TODO.md +++ b/TODO.md @@ -29,6 +29,9 @@ Newest first. An entry ends with its date and its issue or branch, where those are known. +- `README.md` says what a disk that is not mounted does to the database. The + daily `cron` line runs `scan` only when `mountpoint` reports `/srv` as mounted + (2026-11-11, https://git.eeqj.de/sneak/sfdupes/issues/175) - `report` and `trees` leave out a copy that was deleted after the scan. Each checks only the copy itself with `lstat`: the file, or the directory at the top of a tree. A group left with one copy is not reported. A missing `scan`