Automatically creating mount parent directory in merge_debian_isos

test/merge_debian_isos

@@ -27,7 +27,9 @@ usage() {
   echo "xorriso will be run under sudo, if xorriso-dd-target agrees and" >&2
   echo 'the user confirms by input "yes".' >&2
   echo >&2
-  echo "At least the parent directory of mount_template must already exist." >&2
+  echo "At least the parent directory of mount_template must already exist" >&2
+  echo 'or has to be given by a plain name without "/" so that it can be' >&2
+  echo 'created in the current directory. (I.e. without even "./".)' >&2
   echo "All arguments must be single words without using quotation marks." >&2
   echo "None of the isoN must be equal to another isoM." >&2
   echo >&2
@@ -36,11 +38,16 @@ usage() {
   echo "  ./merged_dists , ./merged_md5sum.txt , ./merged_REAMDE.txt" >&2
   echo "  ./temp_file" >&2
   echo "Further it creates and finally removes directories mount_template*" >&2
-  echo "if they are needed and do not exist when the script starts." >&2
-  echo "It depends on the following programs:" >&2
+  echo "if they are needed and do not exist when the script starts. If the" >&2
+  echo "parent directory in the mount_template path does not exist and" >&2
+  echo 'its path contains no "/" then it gets created and finally removed.' >&2
+  echo "The script depends on the following programs:" >&2
   echo "  awk, basename, cat, chmod, cp, date, dirname, expr, fgrep, grep," >&2
   echo "  gunzip, gzip, head, ls, md5sum, mkdir, mount, mv, rm, rmdir," >&2
   echo "  sed, sh, sha256sum, sort, stat, sudo, umount, uniq, xorriso" >&2
+  echo "With device writing involving helper script xorriso-dd-target:" >&2
+  echo "  dd, Linux kernel, lsblk, sleep, tr, uname, wc, whoami," >&2
+  echo "  xorriso-dd-target" >&2
   echo "Recommended are: sha1sum, sha512sum" >&2
   echo >&2
   echo "Exported non-empty variable MERGE_DATE enforces a particular" >&2
@@ -59,29 +66,23 @@ usage() {
   echo >&2
   echo "Example using GNU xorriso-1.5.4 instead of /usr/bin/xorriso:" >&2
   echo "  export XORRISO="'"$HOME"'"/xorriso-1.5.4/xorriso/xorriso" >&2
-  echo "  mkdir merge_mount" >&2
   echo "  $(basename "$0") merged.iso merge_mount/iso "'\' >&2
   echo "                    debian-11.2.0-amd64-DVD-[12345].iso" >&2
-  echo "  rmdir merge_mount" >&2
   echo >&2
   echo "Example writing to optical drive /dev/sr0 :" >&2
-  echo "  mkdir merge_mount" >&2
   echo "  $(basename "$0") mmc:/dev/sr0 merge_mount/iso "'\' >&2
   echo "                    debian-11.2.0-amd64-DVD-[12345].iso" >&2
-  echo "  rmdir merge_mount" >&2
   echo >&2
   echo \
   "Example on Linux writing to USB stick with xorriso-dd-target-plug-test:" >&2
   echo "  wget https://dev.lovelyhq.com/libburnia/libisoburn/raw/master/xorriso-dd-target/xorriso-dd-target" >&2
   echo "  chmod u+x xorriso-dd-target" >&2
   echo '  export XORRISO_DD_TARGET_PATH="$(pwd)"' >&2
-  echo "  mkdir merge_mount" >&2
   echo "  $(basename "$0") xorriso-dd-target-plug-test merge_mount/iso "'\' >&2
   echo "                    debian-11.2.0-amd64-DVD-[12345].iso" >&2
   echo "This leads to the first two steps of the xorriso-dd-target device" >&2
   echo "plug dialog. See: https://wiki.debian.org/XorrisoDdTarget" >&2
   echo 'Finally input "yes" is required to authorize xorriso under sudo.' >&2
-  echo "  rmdir merge_mount" >&2
 }
 
 check_single_word() {
@@ -520,12 +521,21 @@ fi
 MOUNT_TEMPLATE="$2"
 check_single_word "$2" "mount_template" || cleanup_and_end 1
 x=$(dirname "$MOUNT_TEMPLATE")
+mount_parent_to_make=
+mount_parent_made=
 if test -d "$x"
 then
   dummy=dummy
 else
-  echo "--- The parent directory of '${MOUNT_TEMPLATE}' does not exist." >&2
+  # The parent will be temporarily created only if it is a plain leaf name
+  if echo " $x" | fgrep / >/dev/null
+  then
+    echo "--- The parent directory '${x}' of mount_template does not exist" \
+         >&2
+    echo "--- and contains a '/' character. Will not create it." >&2
     cleanup_and_end 1
+  fi
+  mount_parent_to_make="$x"
 fi
 
 shift 2
@@ -575,6 +585,17 @@ echo "Arguments look acceptable." >&2
 echo >&2
 echo "Mounting ISO images if not yet mounted ..." >&2
 
+if test -n "$mount_parent_to_make"
+then
+  if mkdir "$mount_parent_to_make"
+  then
+    mount_parent_made="$mount_parent_to_make"
+  else
+    echo "--- Cannot create the parent directory of '${MOUNT_TEMPLATE}'." >&2
+    cleanup_and_end 1
+  fi
+fi
+
 mount_count=0
 for i in $ISO_LIST
 do
@@ -630,6 +651,12 @@ do
 
   MOUNT_LIST="$MOUNT_LIST $mount_point"
 done
+
+if test -n "$mount_parent_made"
+then
+  RMDIR_LIST="$RMDIR_LIST $mount_parent_made "
+fi
+
 echo "Done." >&2
 
 echo >&2