Introduction to UNIX D UNIX File Structure June

Introduction to UNIX D. UNIX File Structure June 1, 1999 UNIX File System 1

UNIX File System Performance Objectives: 1. 2. 3. 4. 5. 6. 7. Identify types of Files (file) Diagram the relationship of Files and Directories Navigate the UNIX Directory Structure (cd, pwd) Identify pathnames: Absolute (/) and Relative (. . . ~) Define file naming conventions Make and remove directories (mkdir, rmdir) List files and directories and their attributes (ls) June 1, 1999 UNIX File System 2

Types of Files • • • Documents (ordinary files) Directories (help organize other files) Commands Special files - pipe | Hidden files (dot) Devices June 1, 1999 UNIX File System 3

Relation of Files & Directories • Root is like a file cabinet. n n n A directory is like a file drawer A subdirectory is like a folder within a drawer. A path is a list of directories & subdirectories from root to a specific file or subdirectory. / Root Directories Files June 1, 1999 UNIX File System 4

UNIX Directory Structure • At login, you are in your home directory. • This is your current working directory. • All files and directories below your home directory usually belong to you. • You change your working directory by changing to another directory (cd). June 1, 1999 UNIX File System 5

Pathnames • Absolute Pathname: n shows the absolute position of a file or directory in the hierarchy; /home/user 2/bif/docs n begins with a slash (/); and n describes how to get to the file from the root. June 1, 1999 UNIX File System 6

Pathnames • Relative Pathnames: n n Describes how to get to a file from your current working directory. Special characters represent directory locations. è home directory ~ ~chidhkra è current directory. cp ~chidhkra/file. è parent directory. . cp ~chidhkra/file. . June 1, 1999 UNIX File System 7

Filesystems • A file is identified by n n Combining directory pathnames To the filename /usr/local/meeting / root usr files local meeting June 1, 1999 UNIX File System 8

Naming Files • Filenames may be 1 to 255 characters n n UPPER and lowercase, numbers, other ASCII characters, except special Shell characters, control characters and the space. June 1, 1999 UNIX File System 9

Filename DON'TS • Don't begin a filename with a dot (. ) • Don't use any of the following characters ; | ? * {} < > : # () [] ' $ - ~ " ! % & / June 1, 1999 UNIX File System 10

Examples of UNIX File Names: status. memo casey_mt 1. 2. 3 chapter 1 June 1, 1999 UNIX File System 11

Hidden Files (dot) • Used to establish your environment: . cshrc. pinerc . login. forward • Must use ls -a option to view • Always in home directory (some exceptions) June 1, 1999 UNIX File System 12

Naming Conventions • Programs like make, cc, and sccs use a default conventions to name files generated: <f>. o Binary Compiler Output <f>. j FPP output files <f>. i C preprocessor Output <f>. a AR or BLD files <f>. c C/C++ language source code <f>. Z compressed files (use <f>. f Fortran source code uncompress) <f>. mk Makefiles <f>. gz gzipped files (use gunzip) s. <f> SCCS files <f>. tar tape archive (use tar) a. out executable name <f>. l compiler listings June 1, 1999 UNIX File System 13

Identifying File Content • The command file identifies file content: host% file passwd: ascii text host% file ~dhk/* PSaddress: Post. Script document acl: directory address: [nt]roff, tbl, or eqn input text adv. fil: ascii text cfs. size: executable shell script dip: shell commands June 1, 1999 UNIX File System 14

Directory Commands • mkdir • cd • pwd • ls • rmdir June 1, 1999 making a directory changing your working directory printing your working directory listing the contents of a directory removing a directory UNIX File System 15

Directory Commands - mkdir • Make directory under current working directory host% mkdir docs • Make directory under subdirectory host% mkdir docs/index • Make directory and subdirectory host% mkdir docs/index • Make directory using absolute path User 1 (cwd) docs index host% mkdir /usr/tmp/abc June 1, 1999 UNIX File System 16

Common Error Messages: mkdir: dirname: File exists mkdir: dirname: Permission denied June 1, 1999 UNIX File System 17

Directory Commands - cd userx host% cd docs host% cd /usr/tmp/abc/docs /usr tmp abc host% cd ~abc/docs host% cd docs ~abc docs host% cd. . June 1, 1999 UNIX File System 18

Common Error Messages: • pathname: No such file or directory • pathname: Permission denied June 1, 1999 UNIX File System 19

Directory Commands - pwd • Determining the current working directory: host% pwd /scc/users/chitspit/bif • where: / è scc/ è users/ è chitspit/ è bif è June 1, 1999 root file system followed by the delimiter (/) subdirectory of scc directory followed by the delimiter (/) current working directory UNIX File System 20

Directory Commands - ls cwd host% ls bin mbox complex. f outdis remodel test host% ls -s. F (Multiple options may be specified) 15 bin/ 256 mbox 3 remodel/ 34 complex. f 6 outdis@ 1 test* host% ls ~chitspit/bin au clst prod show June 1, 1999 xref UNIX File System 21

Directory Commands - ls • The long list provides additional file information: List alphabetized host% ls -l total 31 drwxr-xr-x -rw-r--r--rw-------rw-r--r-drwxr-xr-x -rwxr-xr-x June 1, 1999 2 1 1 1 2 1 dhk 512 dhk 129 dhk 4291 dhk 512 dhk 10291 UNIX File System Oct Nov Jul Jun Jan Mar 23 20 2 16 22 19 1985 10: 05 14: 18 11: 07 12: 55 bin comp mbox outdis remod test 22

List Hidden Files: ls -a • The -a option lists all files in a directory: host% ls -a. . login. . bin. cshrc complex. f June 1, 1999 mail test public_html remodel UNIX File System 23

Directory Commands - rmdir • The rmdir command removes directories. host% rmdir bif/docs • Directory must be empty. userx bif docs • Common error messages: rmdir: docs: Directory not empty è rmdir: /scc/users/abc/docs: Permission denied è June 1, 1999 UNIX File System 24

End of Module Complete UNIX File Structure Exercises June 1, 1999 UNIX File System 25