Input/Output Redirections

Cat Command

This command is used to concatenate or join files.

cat catfile.txt -n

The -n option tells cat to number all output lines.

> operator

used to redirect output to the new standard output.

> > operator

appends to the file exists or else creates it as a new file and writes the data.

head

useful to see a few lines of a file, typically the first few lines.

10 lines

default of head command

head -3 name.txt

Show the first 3 lines of text in name.txt

head -c10 name.txt

Show the first 10 characters of the name.text

tail

used to show the last few lines of a file.

tail -3 name.txt

show the last 3 in the name.txt file

tail -3 name.txt

Displays the last 3 lines of the name.txt

tail -n4 name.txt

Displays the last 4 lines of the name.txt file

tail -c10 name.txt

Displays the last 10 bytes (characters) of the name.txt file

sort

used to sort the contents of the file and display the sorted list on the standard output (screen).

sort name.txt

Sort the file name.txt in ascending

sort -r name.txt

Sort the name.txt file in Descending

WC Command

stands word count is used to find the number of characters, the number of words, and number of lines in a file.

wc -w file1.txt

Counts the number of Words in the file1.txt

wc -c file1.txt

Counts the number of Characters (bytes) in the file1.txt

wc -l file1.txt

Counts the number of Lines in the file1.txt

grep

one of the most powerful commands in Linux. It matches the given pattern with each line of the file and displays all lines that match the pattern.

grep hope lines.txt

Show the lines that has character pattern hope from the lines.txt and verify the output.

grep lie lines.txt

Show the lines that has character pattern character lie from the lines.txt and verify the output.

pr

used to convert a text file for printing.

pr -3 lines.txt

Show the print preview of lines.txt and names.txt in 3 columns respectively.