edit file with sudo in emacs

• C-x C-f /sudo::/path/to/file RET

get the size of a directory in Linux

• du -sh /var

• du -h –max-depth=1 /var

• from https://linuxize.com/post/how-get-size-of-file-directory-linux/

• from https://linuxhandbook.com/find-directory-size-du-command

data related

• 1 word = 2 byte
• 1 byte = 8 bit
• bps, bits per seconds

host order & network order

• from: https://www.ibm.com/support/knowledgecenter/en/SSB27U_6.4.0/com.ibm.zvm.v640.kiml0/asonetw.htm