Printing output of c program to a file in Linux

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 & error-n-output.file

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


🐧 Get the latest tutorials on Linux, Open Source & DevOps via RSS feed or Weekly email newsletter.

🐧 5 comments so far... add one


CategoryList of Unix and Linux commands
Disk space analyzersdf duf ncdu pydf
File Managementcat cp mkdir tree
FirewallAlpine Awall CentOS 8 OpenSUSE RHEL 8 Ubuntu 16.04 Ubuntu 18.04 Ubuntu 20.04
Modern utilitiesbat exa
Network UtilitiesNetHogs dig host ip nmap
OpenVPNCentOS 7 CentOS 8 Debian 10 Debian 8/9 Ubuntu 18.04 Ubuntu 20.04
Package Managerapk apt
Processes Managementbg chroot cron disown fg glances gtop jobs killall kill pidof pstree pwdx time vtop
Searchingag grep whereis which
User Informationgroups id lastcomm last lid/libuser-lid logname members users whoami who w
WireGuard VPNAlpine CentOS 8 Debian 10 Firewall Ubuntu 20.04
5 comments… add one
  • sairam kunala Aug 18, 2007 @ 17:44

    for redirecting stderr to a file

    command 2> error.file

  • sher Oct 27, 2007 @ 9:06

    offcourse this is very helpful document

  • soraver May 6, 2008 @ 12:40

    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 :)

  • aftab Jun 12, 2011 @ 4:38

    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

  • prakash Nov 21, 2011 @ 6:45

    Thanks a lot dear ,

Leave a Reply

Your email address will not be published.

Use HTML <pre>...</pre> for code samples. Still have questions? Post it on our forum