I Failed the Turing Test

Redirect Console Output: stdout and stderr

Posted on Author VintaPosted in DevOps

File descriptors:

  • 0: stdin
  • 1: stdout
  • 2: stderr
# redirect stdout to a file `test.log`
$ strace uptime > test.log
$ strace uptime 1> test.log

# redirect stderr to a file `test.log`
$ strace uptime 2> test.log

# redirect stderr to stdout
# &1 references the value of the file descriptor 1 (stdout)
$ sh /home/vinta/do_shit.sh > /tmp/do_shit.log 2>&1

# `2> 1` actually means that you redirect stderr to a file named `1`
$ sh /home/vinta/do_shit.sh > /tmp/do_shit.log 2> 1
$ cat 1

# redirect both stderr and stdout to file `test.log`
$ strace uptime &> test.log

# run a command in backgroud
$ long-running-command &

ref:
http://tldp.org/HOWTO/Bash-Prog-Intro-HOWTO-3.html
https://www.cyberciti.biz/faq/redirecting-stderr-to-stdout/
https://www.brianstorti.com/understanding-shell-script-idiom-redirect/