Working with Files

1. Working with Files Chapter 5

2. Display a Calendar • Display a calendar for a specific month • cal 12 2000 • Display a calendar for a specific year • cal 2000 • What if we want to save the calendar?

3. Creating a file with redirection • Most commands send their output to the screen • You can change (redirect) where you want the results sent • cal 2000 > 2001 • Be careful: output redirection will overwrite the target file if it already exists

4. ls list Displays all files in the current directory. Flags: -a: shows all the files, including hidden ones -F: puts a / after directories, an * after executables, and an @ after links -l: displays a long listing of files -R: will also list contents of sub-directories -s: will list the size of the files

5. Viewing the file What if you want to see the contents of a file? Use the cat command cat [name of file] cat 2000 Use the more command more [name of file] more 2000

6. Chaining files together Use the cat command to see more than one file cal 6 2000 > june cal 7 2000 > july cal 8 2000 > august cat june july august Send the results to another file cat june july august > summer2000

7. Appending files Unix allows you to add information to the end of a file rather than overwriting it This is called appending Command output can be appended ‘>>’ cal 9 2000 >> summer2000 The output of the cal command is appended to the end of the file summer2000 On file can be appended to the end of another using cat and redirection cat summer2000 >> myCalendar OR cat myCalendar summer2000 > myCalendar

8. cp Copies the contents of one file to another cp [file to copy] [new file name] Flags -r: will copy directories and all their contents Without this flag, the directory will not be copied and you will get an error message

9. mv Better name could be the rename command Changes the name of one file to another mv [old file name] [new file name] Note, if [new file name] is a directory, you will move [old file name] to that directory and keep the original name

10. rm remove Deletes the specified file or files This is destructive! They are gone! They cannot be retrieved! rm [file name] rm does not work with directories unless the –r option is used

11. touch Touch creates an empty file touch [file name] If the file already exists, touch leaves it contents But it updates the time stamp of the file Used to Test directory permissions Create a sample file Update the time stamp on an existing file

12. lpr print command (stands for “line printer”) This prints the file(s) you specify to the printer you specify lpr [flags] [file name(s) to print] Flags: -P: specifies the name of the printer to print to -w[1-n]: specifies the number of pages to print per page -h: removes the header page

13. lpq view print queue lpq stands for “line printer query” When you print a file, it gets sent to a print queue (a line of files waiting to be printed) lpq will show you the names of the files in the print queue Use the -P flag just like in lpr to specify the printer whose queue you wish to view

14. lprm • line printer remove • Used to remove a file from the print queue • Use the lpq to see the file and then use lprm [job number] to remove the specific job • You can only remove print jobs that you sent to the printer • Use the ‘-’ flag to remove all your files