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