various uses of CAT command

cat-catenate command

• create files
• Display contents of a file
• concatenate files
• Append files

Creating files

• used to create small files
• Takes input from keyboard
• sends output to the monitor
• syntax:   

                         $ cat -options file name

• doesnot allow editing, therefore not used to create large files

Example

$cat>fruits

apple

banana

<ctrl d>

$cat >veg

beans

tomato 

Displaying contents of the file 

• Display only the contents of the file.
• Doesnot display file name , header or EOF marking
• Can display contents of more than a file at a time.

Example

$cat fruits

apple

banana

$cat fruits veg

apple

banana

beans

tomato

Concatenate a file

• Used to concatenate ( merge ) contents of two or more files and store them in another file.

                    $cat file1 file2 >file3

• if file3 doesnot exist then it will create file3, if file exist then the contents in file3 are overwritten

Example

$cat fruits veg > food

$cat food

apple

banana

beans

tomato

Append files

• used to add data to a file 

                            $cat >> fruits

Example

$cat >> fruits

pineapple

<ctrl d>

$cat fruits

apple

banana

pineapple

Cat options

• -v : display nonprintable ASCII characters
• -n : number of lines in a file
• -s: silent no errors

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