Add README.md file

diff --git a/README.md b/README.md
new file mode 100644 (file)
index 0000000..9c8332e
--- /dev/null
+++ b/README.md
@@ -0,0 +1,120 @@
+# Backup Script
+
+
+## Usage
+
+### backup-script
+
+Backup all or individual systems.
+
+Usage: `backup-script [<options>] [<system> [<system> [...]]]`
+
+Options:
+
+- `-p`, `--progress`: Show progress, see rsync(1).
+- `-n`, `--dry-run`: Test run only, don't copy any data.
+
+When no *system* is given, all defined systems are used.
+
+### backup-script-wrapper
+
+Backup all systems and mail the report to "root".
+
+Usage: `backup-script-wrapper`
+
+### backup-status
+
+Show information about backups.
+
+Usage: `backup-status [-q] [<system> [<system> [...]]]`
+
+Options:
+
+- `-q`: *quick mode*, don't calculate backup sizes.
+
+
+## Configuration
+
+All defauklt configuration variables are read from `/etc/backup-script.conf`,
+from `/etc/backup-script.d/backup-script.conf` (deprecated). The individual
+systems are configured using individual files in `/etc/backup-script.d/`, one
+for each system to backup (files ending in `*.sh` are skipped).
+
+Variables in `backup-script.conf` must be prefixed with `default_` to define
+default values for all systems.
+
+All default can be overwritten in individual system configuration files.
+
+For example:
+
+- `/etc/backups-script.conf`: defaults for all hosts
+- `/etc/backups-script.d/host01.example.net`: configuration for host 1
+- `/etc/backups-script.d/clientXY.example.com`: configuration for host 2
+
+
+## Configuration Variable
+
+### system
+
+System host name. Default: file name.
+
+*Note:* There is no `default_system` variable!
+
+### [default_]user
+
+Remote user. Default: `root`.
+
+### [default_]target
+
+Local backup directory. The backup of each system is stored in a folder named
+like the system (see `system` variable) inside of this target directory.
+
+*Note:* There is *no* default, you have to specify this variable, for example as
+`default_target` in the `backups-script.conf` file!
+
+### [default_]ssh_args_add
+
+Additional parameters for `ssh`. Default: none.
+
+### [default_]rsync_args_add
+
+Additional parameters for `rsync`. Default: none.
+
+### [default_]exclude_args_add
+
+Additional (exclude) parameters for `rsync`. Default: none.
+
+### [default_]compress
+
+Enable (1) or disable (0) compression. Default: 1 (on).
+
+### [default_]ping
+
+Enable (1) or disable (0) ping'ing the target system to make sure that it is
+reachable before calling `rsync`. Default: 1 (on).
+
+### [default_]local
+
+Enable (1) or disable (0) *local mode*: when local mode is in effect, `rsync` is
+called without using `ssh`, which is a good idea when saving the local system.
+Default: 0 (off; use ssh).
+
+### [default_]generations
+
+Number of generations to keep. Default: 0 (none).
+
+On a *btrfs* target file systems (see `target` variable), this script can
+generate generations using *btrfs snapshots*: the script creates a new snapshot
+named with the timestamp for each generation inside of the system directory
+inside of the target directory.
+
+### [default_]job_pre_exec
+
+Optional script to execute before `rsync` starts. Default: none.
+
+When the `job_pre_exec` script returns an error (exit code is not 0), the backup
+run is skipped!
+
+### [default_]job_post_exec
+
+Optional script to execute after `rsync` exited. Default: none.