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Working with Files

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Working with Files. Chapter 6.8-6.15, Chapter 7. Display a Calendar ... What if we want to save the calendar? Creating a file with redirection ... – PowerPoint PPT presentation

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Title: 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 gt 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 _at_ 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 gt june
  • cal 7 2000 gt july
  • cal 8 2000 gt august
  • cat june july august
  • Send the results to another file
  • cat june july august gt 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 gtgt
  • cal 9 2000 gtgt 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 gtgt myCalendar OR
  • cat myCalendar summer2000 gt 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
  • -w1-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
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