stdin redirection (<) in Linux CLI - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to read input from a file named 'input.txt' using stdin redirection.

Linux CLI

cat [1]

Drag options to blanks, or click blank then click option'

A< input.txt

B> input.txt

Cinput.txt

D>> input.txt

Attempts:

3 left

💡 Hint

Common Mistakes

Using '>' or '>>' which redirect output instead of input.

Just writing the filename without '<' does not redirect stdin.

Using '< input.txt' redirects the content of 'input.txt' as standard input to the 'cat' command.

2fill in blank

medium

Complete the command to count the number of lines in 'data.txt' using stdin redirection.

Linux CLI

wc -l [1]

Drag options to blanks, or click blank then click option'

A>> data.txt

Bdata.txt

C> data.txt

D< data.txt

Attempts:

3 left

💡 Hint

Common Mistakes

Using the filename without '<' which makes 'wc' treat it as an argument.

Using '>' or '>>' which redirect output, not input.

Using '< data.txt' sends the file content as input to 'wc -l' which counts lines.

3fill in blank

hard

Fix the error in the command to sort the contents of 'list.txt' using stdin redirection.

Linux CLI

sort [1]

Drag options to blanks, or click blank then click option'

Alist.txt

B> list.txt

C< list.txt

D>> list.txt

Attempts:

3 left

💡 Hint

Common Mistakes

Using the filename without '<' which makes 'sort' treat it as an argument.

Using '>' or '>>' which redirect output and overwrite the file.

To sort contents from a file using stdin redirection, use '< list.txt' so 'sort' reads from the file.

4fill in blank

hard

Fill both blanks to filter lines containing 'error' from 'log.txt' using stdin redirection and grep.

Linux CLI

grep [1] [2]

Drag options to blanks, or click blank then click option'

A"error"

B< log.txt

Clog.txt

D-i

Attempts:

3 left

💡 Hint

Common Mistakes

Using the filename as an argument instead of redirecting input.

Forgetting to quote the search pattern.

Use 'grep "error" < log.txt' to search for 'error' in the file by redirecting input.

5fill in blank

hard

Fill all three blanks to print words longer than 5 letters from 'words.txt' using stdin redirection and awk (assuming one word per line).

Linux CLI

awk '[1] [2]' [3]

Drag options to blanks, or click blank then click option'

Alength($0) > 5

B< words.txt

C{print $0}

D> words.txt

Attempts:

3 left

💡 Hint

Common Mistakes

Using '>' instead of '<' for input redirection.

Omitting the print action in awk.

Not quoting the awk script properly.

Use 'awk 'length($0) > 5 {print $0}' < words.txt' to print words (lines) longer than 5 characters from the file.