Fix shellcheck in components/9990-main.sh

Address all issues reported by shellcheck:

```
shellcheck -e SC1091 components/9990-main.sh
```

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

diff --git a/components/9990-main.sh b/components/9990-main.sh
index 530cd3b..4ea8ee1 100755 (executable)
--- a/components/9990-main.sh
+++ b/components/9990-main.sh
@@ -37,7 +37,7 @@ Live ()
        then
                if do_netmount
                then
-                       livefs_root="${mountpoint}"
+                       livefs_root="${mountpoint?}"
                else
                        panic "Unable to find a live file system on the network"
                fi
@@ -52,16 +52,14 @@ Live ()
                else
                        if [ -x /usr/bin/memdiskfind ]
                        then
-                               MEMDISK=$(/usr/bin/memdiskfind)
-
-                               if [ $? -eq 0 ]
+                               if ! MEMDISK=$(/usr/bin/memdiskfind)
                                then
                                        # We found a memdisk, set up phram
                                        # Sometimes "modprobe phram" can not successfully create /dev/mtd0.
                                        # Have to try several times.
                                        max_try=20
-                                       while [ ! -c /dev/mtd0 -a "$max_try" -gt 0 ]; do
-                                         modprobe phram phram=memdisk,${MEMDISK}
+                                       while [ ! -c /dev/mtd0 ] && [ "$max_try" -gt 0 ]; do
+                                         modprobe phram "phram=memdisk,${MEMDISK}"
                                          sleep 0.2
                                          if [ -c /dev/mtd0 ]; then
                                                break
@@ -88,7 +86,7 @@ Live ()
                                fi
 
                                sleep 1
-                               i="$(($i + 1))"
+                               i=$((i + 1))
                        done
                fi
        fi
@@ -132,10 +130,10 @@ Live ()
 
        if [ -n "${MODULETORAMFILE}" ] || [ -n "${PLAIN_ROOT}" ]
        then
-               setup_unionfs "${livefs_root}" "${rootmnt}"
+               setup_unionfs "${livefs_root}" "${rootmnt?}"
        else
                mac="$(get_mac)"
-               mac="$(echo ${mac} | sed 's/-//g')"
+               mac="$(echo "${mac}" | sed 's/-//g')"
                mount_images_in_directory "${livefs_root}" "${rootmnt}" "${mac}"
        fi
 
@@ -173,10 +171,10 @@ Live ()
        else
                DNSFILE="${rootmnt}/etc/resolv.conf"
        fi
-       if [ -f /etc/resolv.conf ] && ! grep -E -q -v '^[[:space:]]*#|^[[:space:]]*$' ${DNSFILE}
+       if [ -f /etc/resolv.conf ] && ! grep -E -q -v '^[[:space:]]*#|^[[:space:]]*$' "${DNSFILE}"
        then
                log_begin_msg "Copying /etc/resolv.conf to ${DNSFILE}"
-               cp -v /etc/resolv.conf ${DNSFILE}
+               cp -v /etc/resolv.conf "${DNSFILE}"
                log_end_msg
        fi
 
@@ -189,8 +187,8 @@ Live ()
        # this includes code that checks what is mounted on /lib/live/mount/*
        # (eg: grep /lib/live /proc/mount)
        # XXX: to be removed before the bullseye release
-       mkdir -p ${rootmnt}/lib/live/mount
-       mount --rbind /run/live ${rootmnt}/lib/live/mount
+       mkdir -p "${rootmnt}/lib/live/mount"
+       mount --rbind /run/live "${rootmnt}/lib/live/mount"
 
        Fstab
        Netbase