Linux Day2

23 Jun 2021 in System Network

Linux directory structure

/ : "root", the top of the file system hierarchy
/bin : Binaries and other executable programs
/etc : System configuration files
/home : Home directories (/home/callie => 내 account 데이터를 저장)
/opt : optional or third party software. (sw that is not bundled with the OS)
/tmp : Temporary space, typically cleared on reboot
/usr : User related programs
/var : Variable data, most notably log files
/var/log : Log files

/boot : Files needed to boot the operating system
/cdrom : Mount point for CD-ROMs.
/dev : device files, typically controlled by the OS and the sys admin
/export : shared file systems
/lib : system libraries
/lib64 : system libraries, 64bit
/lost+found : Used by the file system to store recovered files after a file system check has been performed.
/media : Used to mount removable media like CD-ROMs
/mnt : Used to mount external file systems
/proc : Provides info about running processes
/sbin : System administration binaries
/selinux : Used to display information about SELinux

usr/local : Locally installed software that is not part of the base operating system.

Application Directory Structures

• Applicatinos that are not part of the base OS can be installed in

  /usr/local
  /opt
  

• usr/local/SWname/

/usr/local/crashplan/bin
/usr/local/crashplan/etc
/usr/local/crashplan/lib
/usr/local/crashplan/log

Shell

• The default interface to Linux
• CLI VS GUI
  • The command line is more powerful
  • There will always be a command line
  • Server distributions do not include GUIs.
  • Desktop distributions have GUIs and CLIs
• The prompt
  • $ : Normal user
  • # : Super user root@linuxsvr (superuser account)
• Tilda Expansion
  • ~callie = /home/callie
  • ~pat = /home/pat
  • ~root = /root
  • ~ftp = /srv/ftp

Basic linux commands

ls : Lists directory contents
cd : Changes the curreent directory
pwd : Displays the present working directory
cat : Concatenates and displays files
echo : Displays arguments to the screen
man : Displays the online manual
exit : Exits the shell or your current session
clear : Clears the screen

man cmd 하면 정보 나옴 다 봤으면 q 치고 나간다. man ls 이렇게

PATH

• An environment variable
• Controls the command search path
• Contains a list of directories

which

• Locate a command

cd /bin  
man 명령어

How to use directory shortcuts

. : This directory
.. : The parent directory
cd - : Change to the previous dirctory

How to execute commands outside of $PATH

• $PATH 안에 있는 디렉토리의 명령어라면 , 어디에든지 불러도 실행된다.
• ./(디렉토리에 있는 명령어) : 이렇게 실행 가능하다.

How to create and remove directories

mkdir [-p] directory : Create a directory
rmdir [-p] directory : Remove a directory
rm -rf directory : Recursively removes directory

• -p 넣으면 /a/b 이렇게 만들면 a 패런트 디렉토리도 만들어준다.

mkdir dir1/dir2/dir3  : 오류 뜬다.
mkdir -p dir1/dir2/dir3 : 정상 실행됨.

ls

ls -l : 파일 정보 
ls -a : hidden file까지 보여줌
ls -al : 이렇게 한번에 할 수 있다.
ls -F : 파일, 디렉토리 타입 알려준다. / : 디렉토리, @ : link , * : 실행가능한

Permission, Number of links, Owner name, Group name, Number of bytes in the file, Last modification time, File name

ls -t : list files by time
ls -r : reverse order
ls -latr : Long listing including all files reverse sorted by time
ls -R : lists files recursively 
ls -R은 tree와 비슷하다. tree -d(디렉토리만), tree -C(colored)와 미슷하다.

이름에 스페이스가 있을 때, ““를 이용한다.

ls -l "my notes.txt"