modify fstab instead of replacing in order to keep modifications made

Changelog: The fstab file from the image being converted is now preserved across convertions, with the Mender specific additions merged with the existing fstab file, as opposed to replacing it completely. Which was the previous approach.

Signed-off-by: Simon Ensslen <simon.ensslen@griesser.ch>

configs/mender_convert_config

@@ -32,6 +32,9 @@ MENDER_ARTIFACT_COMPRESSION="gzip"
 # this.
 MENDER_ENABLE_SYSTEMD=y
 
+# Set the fstab options for mounting the boot partition
+MENDER_BOOT_PART_FSTAB_OPTS="defaults,sync"
+
 # Custom mkfs options for creating the rootfs partition
 MENDER_ROOT_PART_MKFS_OPTS=""
 

mender-convert-modify

@@ -356,14 +356,17 @@ fi
 log_info "Using boot partition device in fstab: $boot_part_device"
 log_info "Using data partition device in fstab: $data_part_device"
 
-sudo bash -c "cat <<- EOF > work/rootfs/etc/fstab
-# stock fstab - you probably want to override this with a machine specific one
+fstab=$(sed '/\/boot/d' work/rootfs/etc/fstab)
+fstab=$(sed '/.*\s\/\s.*/d' <<< "$fstab")
+cat <<- EOF > work/rootfs/etc/fstab
+${boot_part_device}   ${boot_part_mountpoint}          auto       ${MENDER_BOOT_PART_FSTAB_OPTS}    0  0
 /dev/root            /                    auto       ${MENDER_ROOT_PART_FSTAB_OPTS} 1  ${MENDER_ROOT_PART_FS_PASSNO}
-proc                 /proc                proc       defaults              0  0
 
-${boot_part_device}   ${boot_part_mountpoint}          auto       defaults,sync    0  0
 ${data_part_device}   /data          auto       ${MENDER_DATA_PART_FSTAB_OPTS}      0  0
-EOF"
+
+# entries kept from original fstab
+$fstab
+EOF
 
 #
 # Make sure to re-label rootfs when selinux is in enforcing mode