tee command in Linux with examples

tee command reads the standard input and writes it to both the standard output and one or more files. The command is named after the T-splitter used in plumbing. It basically breaks the output of a program so that it can be both displayed and saved in a file. It does both the tasks simultaneously, copies the result into the specified files or variables and also display the result.

SYNTAX:

tee [OPTION]... [FILE]...

Options :
1.-a Option : It basically do not overwrite the file but append to the given file.
Suppose we have file1.txt

Input: geek
       for
       geeks

and file2.txt

Input:geeks
      for
      geeks

SYNTAX :

geek@HP:~$ wc -l file1.txt|tee -a file2.txt

OUTPUT :

3 file1.txt

geek@HP:~$cat file2.txt
OUTPUT:
      geeks
      for
      geeks
      3 file1.txt

2.–help Option : It gives the help message and exit.
SYNTAX :

geek@HP:~$ tee --help

3.–version Option : It gives the version information and exit.
SYNTAX :

geek@HP:~$ tee --version

Application

Suppose we want to count number of characters in our file and also want to save the output to new text file so to do both activities at same time, we use tee command.

geek@HP:~$ wc -l file1.txt| tee file2.txt
OUTPUT:
geek@HP:~$15 file1.txt

Here we have file1 with 15 characters, so the output will be 15 and the output will be stored to file2. In order to check the output we use :

geek@HP:~$ cat file2.txt
OUTPUT:
geek@HP:~$15 file1.txt