File system

The UNIX File System naming standards can be located here. Relevant folders for a software engineer are:

• /opt/ contains optional application software (end user programs, such as Chrome, Gradle, etc.):

  /opt/
  ├── containerd
  ├── google
  └── gradle

• /etc/ contains host-specific system-wide configuration files.

• /etc/opt/ contains configuration files for add-on packages that are stored in /opt.

• /var/ contains variable files whose content is expected to continually change during normal operation of the system—such as logs, spool files, and temporary e-mail files.

• /var/opt/ contains variable data from add-on packages that are stored in /opt.

• /var/log/ contains various logs.

• /usr/bin/ (secondary hierarchy) contains the majority of read-only multi-user non-essential (to single-user mode) command binaries:

/usr/bin/
├── ps
├── ls
├── cat
├── bash
├── sh

• /usr/local/bin/ contains scripts used for opening files and project from the command line:

/usr/local/bin/
├── docker-compose
└── idea

• /proc/ contains virtual filesystem providing process and kernel information as files.

• /dev/ contains device files, e.g., /dev/null, /dev/disk0, /dev/sda1, /dev/tty, /dev/random.