Linux learning jottings(1)-system directory

System directory

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directories under "/"

• /bin/: to store user command, a little similar with /usr/bin/
• /sbin/: for system command, a little similar with /usr/sbin/
• /root/ root user(super user)'s home directory
• /mnt/ include the mount point of file system mounted after system boot
• /boot/ files used when kernel and other system boots
• /lost+found/ fsck(file system check) use this directory to store scattered files(some file unnamed)
• /lib/ include some library file used by command in /bin/ or /sbin/
• /dev/ device files
• /etc/ configuration files and directories
• /var/ variable files(or files keep being modified), like log file or printer spooling files
• /usr/ include most things related to system users, like applications and supported library files
• /proc/ a virtual file system (actually not store on disk), include contains some system information used by some applicetion
• /initrd/ somethings used to boot your system, DO NOT DELETE IT
• /tmp/ temporary directory for application and users, every one could read and write files in this directory
• /home/ users' home directory
• /opt/ optional files, used for developers to install or uninstall their software packages easily.

/lib & /usr/lib & /usr/local/lib

1. usr is the abbrviation of Unix System resource
2. simply
   • /lib is kernel level
   • /usr/lib is system level(in CentOS7 both two directories in / was linked to same name dir in /usr/)
   • /usr/local/lib is user level