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--- fuss:linux [2020/05/12 23:36] – [Scraping a Site Automatically using SystemD] office
+++ fuss:linux [2021/04/16 19:21] – [Self-Delete Shell Script] office
@@ Line 1180: / Line 1180: @@
 Upon every reboot, the service file will create a detached tmux terminal and start scraping files from the URL.
+====== Access Directory Underneath Mountpoint ======
+In order to access a directory underneath a mountpoint without unmounting, create a bind mount of the root filesystem to a directory and then access the content via the bind mount.
+Ie, to access the contents of the directory ''/mnt/usb'' on top of which a filesystem has been mounted, create a directory:
+<code bash>
+mkdir /mnt/root
+</code>
+and create a bind mount:
+<code bash>
+mount -o bind / /mnt/root
+</code>
+Finally access the original underlying content via the path ''/mnt/root/mnt/usb2''.
+====== Self-Delete Shell Script ======
+<code>
+rm -rf -- "$@"
+</code>
+====== Resize Last Partition and Filesystem in Image File ======
+Assuming that an image file is available and named, for example, ''raspios.img'' then the following procedure will extend the last partition and the filesystem by a given size.
+First, extend the image file ''raspios.img'' itself with zeroes:
+<code bash>
+dd if=/dev/zero bs=1M count=500 >> raspios.img
+</code>
+where:
+  * ''1M'' is the block size,
+  * ''500'' is the amount of blocks to copy over
+In this case, the image file ''raspios.img'' is extended by $500MiB$. Alternatively, ''qemu-img'' can be used to extend the image file:
+<code bash>
+qemu-img resize raspios.img +500M
+</code>
+The next step is to run ''parted'' and extend the last partition inside the image file. Open the image file with ''parted'':
+<code bash>
+parted raspios.img
+</code>
+and then resize the partition, for example:
+<code bash>
+(parted) resizepart 2 100%
+</code>
+where:
+  * ''2'' is the partition number
+The ''parted'' command will resize the second partition to fill 100% of the available space (in this example, it will extend the second partition by $500MiB$).
+The final step is to enlarge the filesystem within the second partition that has just been extended by $500MiB$. ''kpartx'' will create mapped devices for each of the partitions contained within the ''raspios.img'' image file:
+<code bash>
+kpartx -avs raspios.img
+</code>
+First, the existing filesystem has to be checked:
+<code bash>
+e2fsck -f /dev/mapper/loop0p2
+</code>
+where:
+  * ''/dev/mapper/loop0p2'' is the last partition reported by ''kpartx''
+and then finally the filesystem is extended to its maximum size:
+<code bash>
+resize2fs /dev/mapper/loop0p2
+</code>