Port scripts to strict POSIX implementations (#41)

This commit refactors scripts to pure POSIX implementations.

* Testing was done in `dash` on macOS as well as FreeBSD's `sh` shell.
* Test cases in `test/*.sh` have been significantly improved.
* This is the current recommended version of this script.

.github/workflows/status-checks.yaml

@@ -54,7 +54,7 @@ jobs:
           level: info
           filter_mode: nofilter
           fail_on_error: true
-          shfmt_flags: '-ln bash -ci -sr -i 2'
+          shfmt_flags: '-ci -sr -i 2'
 
   shellcheck:
     name: runner / shellcheck
@@ -76,6 +76,6 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
-      - run: bash ./test.sh
+      - run: cd test && ./test.sh
         env:
           TMPDIR: ${{ runner.temp }}

README.md

@@ -1,9 +1,10 @@
 # zfs-replicate
 
-A Bash script to automate ZFS Replication.
+A POSIX shell script to automate ZFS Replication.
 
 ## Features
 
+- The script follows strict POSIX standards and should be usable on any host with a POSIX compliant shell.
 - Source pools and datasets are always authoritative, the script will always defer to the source.
 - Supports push and pull replication with local and remote datasets.
 - Supports multiple pool/dataset pairs to replicate.
@@ -12,8 +13,8 @@ A Bash script to automate ZFS Replication.
 - Includes a well documented `config.sh` file that may be used as configuration or as reference for environment
   variables passed to the script.
 - May be run on any schedule using cron or similar mechanism.
-- May be sourced and/or leveraged by/in other Bash scripts.
-- Test coverage of core functions via mocks in the test.sh script.
+- Fully source compliant and may be used by other scripts.
+- Test coverage of core functions via mocks in the test/test.sh script.
 - Includes a `--status` option for XigmaNAS that can be used to email the last log output at your preferred schedule.
   Simply add it as a custom script in the email settings under "System > Advanced > Email Reports"
 
@@ -54,18 +55,18 @@ is not met.
 ```text
 Usage: ./zfs-replicate.sh [options] [config]
 
-Bash script to automate ZFS Replication
+POSIX shell script to automate ZFS Replication
 
 Options:
-  -c, --config <configFile>    bash configuration file
+  -c, --config <configFile>    configuration file
   -s, --status                 print most recent log messages to stdout
   -h, --help                   show this message
 ```
 
 ### Config File and Environment Variable Reference
 
-```bash
-#!/usr/bin/env bash
+```sh
+#!/usr/bin/env sh
 ## zfs-replicate configuration file
 # shellcheck disable=SC2034
 
@@ -210,18 +211,18 @@ Options:
 ##
 #FIND=$(which find)
 
-## Path to the system "zfs" binary. The default uses the first "zfs"
-## executable found in $PATH.
-##
-#ZFS=$(which zfs)
-
 ## Path to the system "ssh" binary. You may also include custom arguments
 ## to SSH here or in the "DEST_PIPE_WITH_HOST" option above.
 ## Example: SSH="ssh -l root" to login as root to target host.
 ## The default uses the first "ssh" executable found in $PATH.
 ##
 #SSH=$(which ssh)
 
+## Path to the system "zfs" binary. The default uses the first "zfs"
+## executable found in $PATH.
+##
+#ZFS=$(which zfs)
+
 ## Set the pipe to the destination pool. But DO NOT INCLUDE the pipe (|)
 ## character in this setting. Filesystem  names from the source will be
 ## sent to the destination. For increased transfer speed to remote hosts you

config.sample.sh

@@ -1,4 +1,4 @@
-#!/usr/bin/env bash
+#!/usr/bin/env sh
 ## zfs-replicate configuration file
 # shellcheck disable=SC2034
 
@@ -143,18 +143,18 @@
 ##
 #FIND=$(which find)
 
-## Path to the system "zfs" binary. The default uses the first "zfs"
-## executable found in $PATH.
-##
-#ZFS=$(which zfs)
-
 ## Path to the system "ssh" binary. You may also include custom arguments
 ## to SSH here or in the "DEST_PIPE_WITH_HOST" option above.
 ## Example: SSH="ssh -l root" to login as root to target host.
 ## The default uses the first "ssh" executable found in $PATH.
 ##
 #SSH=$(which ssh)
 
+## Path to the system "zfs" binary. The default uses the first "zfs"
+## executable found in $PATH.
+##
+#ZFS=$(which zfs)
+
 ## Set the pipe to the destination pool. But DO NOT INCLUDE the pipe (|)
 ## character in this setting. Filesystem  names from the source will be
 ## sent to the destination. For increased transfer speed to remote hosts you

test/find.sh

@@ -0,0 +1,14 @@
+#!/usr/bin/env sh
+## test/zfs.sh
+set -eu
+
+# check pipefail in a subshell and set if supported
+# shellcheck disable=SC3040
+(set -o pipefail 2> /dev/null) && set -o pipefail
+
+_fakeFIND() {
+  printf "find %s\n" "$*"
+  return 0
+}
+
+_fakeZFS "$@"

test/ssh.sh

@@ -0,0 +1,25 @@
+#!/usr/bin/env sh
+## test/zfs.sh
+set -eu
+
+# check pipefail in a subshell and set if supported
+# shellcheck disable=SC3040
+(set -o pipefail 2> /dev/null) && set -o pipefail
+
+_fakeSSH() {
+  host=$1
+  shift
+  cmd=$1
+  shift
+  case "$cmd" in
+    *zfs*)
+      ./zfs.sh "$@"
+      ;;
+    *)
+      printf "ssh $host $cmd %s\n" "$*"
+      ;;
+  esac
+  return 0
+}
+
+_fakeSSH "$@"