Fix (nearly) all issues found by shellcheck

shellcheck found more issues than SC1074. Address most of these issues.
You can check the shell code by running:

```
shellcheck -e SC1090,SC1091 -s dash hook-functions $(find * -type f
\( -executable ! -name rules -o -regex '.*\.\(post\|pre\).*'
-o -regex "^\(docs\|scripts\)/.*" ! -name '*.md' \))
```

Signed-off-by: Benjamin Drung <benjamin.drung@cloud.ionos.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/lsinitramfs b/lsinitramfs
index a96308d..4f91a6c 100755
--- a/lsinitramfs
+++ b/lsinitramfs
@@ -4,7 +4,7 @@ set -eu
 
 usage()
 {
-	echo "Usage: $(basename $0) [-l] <initramfs file>"
+	echo "Usage: $(basename "$0") [-l] <initramfs file>"
 }
 
 if [ "$#" -eq 0 ] ; then
@@ -14,7 +14,7 @@ fi
 
 umi_opts="--list"
 
-OPTIONS=`getopt -o hl --long help,long -n "$0" -- "$@"`
+OPTIONS=$(getopt -o hl --long help,long -n "$0" -- "$@")
 # Check for non-GNU getopt
 if [ $? != 0 ] ; then echo "W: non-GNU getopt" >&2 ; exit 1 ; fi