void clear_inode_metadata(ext2_filsys &fs, ext2_ino_t inode_num)
{
    ext2_inode inode;
    ext2fs_read_inode(fs, inode_num, &inode);

    inode.i_mode = 0;                        
    inode.i_links_count = 0;       
    inode.i_size = 0;            
    inode.i_size_high = 0;          
    inode.i_blocks = 0;          
    memset(inode.i_block, 0, sizeof(inode.i_block)); 

    ext2fs_write_inode(fs, inode_num, &inode);  // Write the cleared inode back to disk
}


void delete_file(const string &path, ext2_filsys &fs, const string &device)
{
    ext2_ino_t inode_num = fetch_file(path, fs, device);
    if (inode_num != 0)
    {
        overwrite_blocks(fs, device, path); // traverses extents and writes random data
        clear_inode_metadata(fs, inode_num);
    }

}

$ sum_sofar=0; for file in $(for i in $(seq 1 4); do echo page_$i.pnm; done | xargs echo); do sum_sofar=$((sum_sofar + $(stat -c%s "$file"))); done; echo "The sum of the sizes of the PNM files is $sum_sofar bytes."
The sum of the sizes of the PNM files is 415300162 bytes.
$ convert $(for i in $(seq 1 4); do echo page_$i.pnm; done | xargs echo) -compress Zip -quality 100 -density 1200 tmp_output_document.convert.pdf && pdftk tmp_output_document.convert.pdf update_info  Producer:        https://imagemagick.org 
> CreationDate:    …
> ModDate:         …
16,17c16,17
 File size:       254364579 bytes
> Optimized:       no

exiv2 -M"set Exif.Photo.DateTimeOriginal 2018:09:18 20:11:04" 20180918_201104.jpg

$ opusinfo audio_with_cover.opus
Processing file "audio_with_cover.opus"...

New logical stream (#1, serial: 39a74bbb): type opus
Encoded with libopus 1.3.1
User comments section follows...
	ENCODER=opusenc from opus-tools 0.1.10
	METADATA_BLOCK_PICTURE=3|image/jpeg||1280x720x24|
	ENCODER_OPTIONS=--bitrate 56
Opus stream 1:
	Pre-skip: 312
    [...]

$ ffprobe audio_with_cover.opus 
[ogg @ 0x55675650ca80] 761 bytes of comment header remain
Input #0, ogg, from 'audio_with_cover.opus':
  Duration: 00:02:25.64, start: 0.000000, bitrate: 71 kb/s
  Stream #0:0: Audio: opus, 48000 Hz, stereo, fltp
    Metadata:
      ENCODER         : opusenc from opus-tools 0.1.10
      ENCODER_OPTIONS : --bitrate 56
  Stream #0:1: Video: mjpeg (Baseline), yuvj420p(pc, bt470bg/unknown/unknown), 1280x720, 90k tbr, 90k tbn (attached pic)
    Metadata:
      comment         : Cover (front)

$ ls-alt --show-descriptions /
    ...
    /etc – Configuration Files
    /opt – Optional Software
    /bin - Binaries
    /sbin – System Binaries
    /tmp – Temporary Files
    ...

$ ls-alt --show-descriptions-verbose /
    ...
    /etc – The /etc directory contains the core configuration files of the system, use primarily by the administrator and services, such as the password file and networking files.
    /opt – Traditionally, the /opt directory is used for installing/storing the files of third-party applications that are not available from the distribution’s repository.
    /bin - The ‘/bin’ directly contains the executable files of many basic shell commands like ls, cp, cd etc. Mostly the programs are in binary format here and accessible by all the users in the Linux system.
    /sbin – This is similar to the /bin directory. The only difference is that is contains the binaries that can only be run by root or a sudo user. You can think of the ‘s’ in ‘sbin’ as super or sudo.
    /tmp – This directory holds temporary files. Many applications use this directory to store temporary files. /tmp directories are deleted when your system restarts.
    ...