# Pipe in Linux
-> The output of one commad redirect it to the input of other command
## Pipe syntax
We use '|' symbol to separate two commands. Output of first command passed to second command
```
command1 | command2
```
## Q1. Find number of files in a directory
```sh
ls -1 | wc -l
```
### Breakdown of the command used above
```sh
ls -1
```
The command lists all files in a directory in a single column i.e. a single line represents name of one file.
Output of ls command
```sh
wc -l
```
This prints the number lines in file. Together the commands will print the number of files in a directory.
## Q2. Combine two files and sort them
Combining 2 files using cat command and then sorting them using pipe
```sh
cat file1.txt file2.txt | sort
```
sorted output of concatenation of two files
## Q3. Unique names in a file
{% code fullWidth="true" %}
```sh
cat file3.txt | sort | uniq
```
{% endcode %}
We can only use `uniq` command with sorted data only
## Q4. See 30-37 lines in a file
`head -37` to view first 37 lines , `tail -7` to view last 7 lines from the 37 lines, which makes 30-37
## Tee command -
`tee` command reads from ***stdin*** and saves the content to a file and also displays it to ***stdout***
