Lecture 3: Utilities ( ch 3)

1. Lecture 3: Utilities (ch 3) IT244 - Introduction to Linux / Unix Instructor: Bo Sheng

2. Outline • Special characters in Linux/Unix • Basic utilities • Display / copy / delete files • Sort / search in files • Compare files, obtain file information • Pipe

3. Special Characters • List on Pg50 • Avoid unnecessary use • Treat them differently

4. Special Characters • Examples • echo hello world > hello • cat hello • echo hello * world > hello • cat hello • echo hello ~ world > hello • cat hello

5. Special Characters • Use quote “ ” or ‘ ’ • echo “hello * world” > hello • echo hello “**” world > hello • echo ‘hello ~ world’ > hello • echo hello ‘~~’ world > hello

6. Special Characters • Use \ • echo hello \* world > hello • echo hello \*\* world > hello • Invisible/control characters • CTRL-C, CTRL-U, … • Use CTRL-V

7. Special Characters • Special characters in file names • Create a file “hello world” • echo HELLO WORLD > hello world • ls • cat hello • echo HELLO WORLD > “hello world” • echo HELLO WORLD > hello\ world

8. Special Characters • List on Pg50 • Avoid unnecessary use • Treat them differently • The safe way is to use “ ” or ‘ ’

9. Basic Utilities • Preparation • cd /home/your username/it244 • pwd(make sure of the working directory) • /home/shengbo/it244/prep

10. Basic Utilities • List files • ls –l Size File name

11. Basic Utilities • Display files • cat linux • more linux • less linux

12. Basic Utilities • Display files • head linux • tail linux • head –1 linux • tail –5 linux

13. Basic Utilities • Copy files • cp source-filedestination-file • cp linuxlinux.copy • ls • cp /home/shengbo/it244/welcome welcome • ls • more welcome

14. Basic Utilities • Copy files • Overwriting • cp hello linux • cat linux • “-i” option • cp –i hello linux • cp linux.copylinux(restore file ‘linux’)

15. Basic Utilities • Rename files ( mv ) • ls • mvlinux.copymylinux • ls • Overwriting • cat mylinux • cat hello • mvmylinux hello • cat hello • “-i” option

16. Basic Utilities • Delete files ( rm ) • rm hello • Safe way of deleting (“-i” option) • echo “hello world” > hello • rm –i hello

17. Basic Utilities • Display a file in order ( sort ) • sort linux • sort days • sort –r months • sort days months • Remove duplicate lines • cat dups • uniqdups

18. Basic Utilities • Compare two files ( diff ) • diff –u colors.1 colors.2 colors.1 colors.2 red green yellow pink purple orange red blue green yellow orange

19. Basic Utilities • Compare two files ( diff ) • diff –u colors.1 colors.2 • diff –y colors.1 colors.2 • diff –y colors.1 colors.2 –W 30

20. Basic Utilities • Identify file types ( file ) • file linux • file hello • file /home/shengbo/it244/exetest • file /home/shengbo/it244/umb.jpg

21. Basic Utilities • Word counter ( wc ) • wclinux • wc –l months • wc –w hello • Try inputting control characters in a file lines words chars

22. Basic Utilities • Search a string in files • grep “Linux” linux • grep ‘J’ months • grep n months days

23. Basic Utilities • Pipe (communication between commands) • command1 | command 2 • sort months | head -4 • ls | wc –w • ls | grep “color” • ls /home | more

24. Summary • Special characters • Basic utilities • ls, cat, more, less, head, tail • cp, mv, rm(overwrite, ‘-i’) • sort, uniq, diff, file, wc, grep • | (pipe)

25. Questions • How to display the lines in the middle of a file? For example, in file ‘months’, display from “May” to “Sep”. • uniq can only remove successive duplicate lines. How to remove all the duplicate lines in a file? e.g., display ‘Mary’ only once when operating on file ‘dups’.