bash scripts: use /usr/bin/env for bash shebangs

Not all systems / distros have a `/bin/bash`, and these scripts are
more difficult to run at development time.

For example, my system is NixOS which doesn't have a /bin/bash. This
is not a problem for NixOS building ZFS as a package: the build
environment automatically replaces these shebangs with corrected
paths.

The problem is much more annoying at development time: either the
scripts don't run, or I correct them for my local machine and deal with
a perpetually dirty work tree.

Before committing this patch I confirmed there are existing scripts
which use `/usr/bin/env` to locate bash, so I am thinking this is a
safe transformation.

There are a handful of other shebangs in this repository which don't
work on my system. This patch is useful on its own specifically for
`commitcheck.sh`, otherwise I can't validate my commits before
submission.

Here are the remaining shebangs which NixOS systems won't have:

       1274 #!/bin/ksh -p
         91 #!/bin/ksh
         89 #! /bin/ksh -p
          2 #!/bin/sed -f
          1 #!/usr/bin/perl -w
          1 #!/usr/bin/ksh
          1 #!/bin/nawk -f

plus this which will create an invalid shebang in
`tests/zfs-tests/tests/functional/mv_files/mv_files_common.kshlib`:

        echo "#!/bin/ksh" > $TEST_BASE_DIR/exitsZero.ksh

I chose to leave those alone for now, and gauge the interest in this
much smaller patch first.

The fixes for these are easy enough by simply using `/usr/bin/env ksh`:

         91 #!/bin/ksh
          1 #!/usr/bin/ksh

The fix for the other set is much trickier. Quoting the GNU coreutils
manual:

    Most operating systems (e.g. GNU/Linux, BSDs) treat all text after
    the first space as a single argument. When using env in a script it
    is thus not possible to specify multiple arguments.

and not all `env`'s support arguments.

Mine (GNU Coreutils 8.31) does, though this feature is new since
April 2018, GNU Coreutils 8.30:
https://git.savannah.gnu.org/cgit/coreutils.git/commit/?id=668306ed86c8c79b0af0db8b9c882654ebb66db2

and worse, requires the -S argument:

    -S, --split-string=S  process and split S into separate arguments;
                          used to pass multiple arguments on shebang
                          lines

Example:

    $ seq 1 2 | $(nix-build '<nixpkgs>' -A coreutils)/bin/env "sort -nr"
    /nix/[...]-coreutils-8.31/bin/env: ‘sort -nr’: No such file or directory
    /nix/[...]-coreutils-8.31/bin/env: use -[v]S to pass options in shebang lines

    $ seq 1 2 | $(nix-build '<nixpkgs>' -A coreutils)/bin/env "-S sort -nr"
    2
    1

GNU Coreutils says FreeBSD's `env` does, though I wonder if FreeBSD's
would be unhappy with the `-S`:
https://www.gnu.org/software/coreutils/manual/html_node/env-invocation.html#env-invocation

BusyBox v1.30.1 does not, and does not have a `-S`-like option:

    $ seq 1 2 | $(nix-build '<nixpkgs>' -A busybox)/bin/env "sort -nr"
    env: can't execute 'sort -nr': No such file or directory

Toybox 0.8.1 also does not, and also does not have a `-S` option:

    $ seq 1 2 | $(nix-build '<nixpkgs>' -A toybox)/bin/env "sort -nr"
    env: exec sort -nr: No such file or directory

---

At any rate, if this patch merges and the remaining ~1,500 are updated,
the much larger patch should probably include a checkstyle-like test
asserting all new shebangs use `/usr/bin/env`. I also don't mind
dealing with NixOS weirdness if the project would prefer that.

Reviewed-by: Brian Behlendorf <[email protected]>
Reviewed-by: Ryan Moeller <[email protected]>
Signed-off-by: Graham Christensen <[email protected]>
Closes #9893 

10 files changed, 10 insertions, 9 deletions

diff --git a/cmd/zgenhostid/zgenhostid b/cmd/zgenhostid/zgenhostid
index db690eca3..8b468740c 100755
--- a/cmd/zgenhostid/zgenhostid
+++ b/cmd/zgenhostid/zgenhostid
@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 # Emulate genhostid(1) available on RHEL/CENTOS, for use on distros
 # which do not provide that utility.
diff --git a/contrib/dracut/02zfsexpandknowledge/module-setup.sh.in b/contrib/dracut/02zfsexpandknowledge/module-setup.sh.in
index c22141f00..a2a3ef037 100755
--- a/contrib/dracut/02zfsexpandknowledge/module-setup.sh.in
+++ b/contrib/dracut/02zfsexpandknowledge/module-setup.sh.in
@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 get_devtype() {
   local typ
diff --git a/contrib/dracut/90zfs/module-setup.sh.in b/contrib/dracut/90zfs/module-setup.sh.in
index 4efc4b018..e94f9f2dc 100755
--- a/contrib/dracut/90zfs/module-setup.sh.in
+++ b/contrib/dracut/90zfs/module-setup.sh.in
@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 check() {
 	# We depend on udev-rules being loaded
diff --git a/contrib/dracut/90zfs/zfs-generator.sh.in b/contrib/dracut/90zfs/zfs-generator.sh.in
index 0b8a8aaca..120b9ecf9 100755
--- a/contrib/dracut/90zfs/zfs-generator.sh.in
+++ b/contrib/dracut/90zfs/zfs-generator.sh.in
@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 echo "zfs-generator: starting" >> /dev/kmsg
 
diff --git a/copy-builtin b/copy-builtin
index 700e6f4f0..81fd17565 100755
--- a/copy-builtin
+++ b/copy-builtin
@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 set -e
 
diff --git a/scripts/commitcheck.sh b/scripts/commitcheck.sh
index 2954b0fd7..c7515c23e 100755
--- a/scripts/commitcheck.sh
+++ b/scripts/commitcheck.sh
@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 REF="HEAD"
 
diff --git a/scripts/kmodtool b/scripts/kmodtool
index b928c9286..240cde310 100755
--- a/scripts/kmodtool
+++ b/scripts/kmodtool
@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 # kmodtool - Helper script for building kernel module RPMs
 # Copyright (c) 2003-2012 Ville Skyttä <[email protected]>,
diff --git a/scripts/zimport.sh b/scripts/zimport.sh
index d7e82fe9f..304ab7623 100755
--- a/scripts/zimport.sh
+++ b/scripts/zimport.sh
@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 #
 # Verify that an assortment of known good reference pools can be imported
 # using different versions of the ZoL code.
diff --git a/tests/zfs-tests/include/commands.cfg b/tests/zfs-tests/include/commands.cfg
index 79f05e54a..77562700c 100644
--- a/tests/zfs-tests/include/commands.cfg
+++ b/tests/zfs-tests/include/commands.cfg
@@ -131,6 +131,7 @@ export SYSTEM_FILES_FREEBSD='chflags
     uncompress'
 
 export SYSTEM_FILES_LINUX='attr
+    bash
     blkid
     blockdev
     chattr
diff --git a/tests/zfs-tests/tests/perf/scripts/prefetch_io.sh b/tests/zfs-tests/tests/perf/scripts/prefetch_io.sh
index 75bf08f4b..b8d8ae885 100755
--- a/tests/zfs-tests/tests/perf/scripts/prefetch_io.sh
+++ b/tests/zfs-tests/tests/perf/scripts/prefetch_io.sh
@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 #
 # This file and its contents are supplied under the terms of the