Printing output of c program to a file in Linux

in Categories , , , , last updated August 17, 2007

Q. I’ve written a small program that does something useful for me. I always get output on screen. Sometime I need to send output to a file. How do I print output of my program to a file w/o making any changes to code?

A. Bash shell (and many other modern UNIX shell) supports the concept of I/O redirection It allows you to redirect standard output (screen), standard error and standard input (keyboard) using the following syntax.
command > output.file
command < input.file command >& error-n-output.file

So to redirect output of your own C program just enter:
$ ./myprogr > output.txt
$ cat output.txt

Posted by: Vivek Gite

The author is the creator of nixCraft and a seasoned sysadmin and a trainer for the Linux operating system/Unix shell scripting. He has worked with global clients and in various industries, including IT, education, defense and space research, and the nonprofit sector. Follow him on Twitter, Facebook, Google+.

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5 comment

  1. in addition by using
    command >> file
    you can reuse the same file without deleting the previous data.
    >> adds text to the end of the file :)

  2. Thanks a lot for that,
    But is there a way i can write the output of a c program into a file from WITHIN THE PROGRAM. For example, i know this doesnt work, but what can i do to repliacte this

    system(“ls”) > t1.txt

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