I/O Redirection
I/O Redirection is a cool thing with bash, you can choose where you want the output of a command or script to go. For example try this:
dave@[datadyne]:~/$ echo "hello" > file.txt
dave@[datadyne]:~/$ cat file.txt
hello
Recall that cat prints the contents of a file. We can also do that with a
script, try this:
dave@[datadyne]:~/$ bash script.sh > file.txt
dave@[datadyne]:~/$ cat file.txt
Hello Dave, you are 21 years old!
As you can see the scripts output was written to file.txt, but the last thing written to it is gone! That's because the > operator will wipe out anything in the file when you use it. If you want to concatenate it with the file, use the >> operator.
dave@[datadyne]:~/$ bash script.sh > file.txt
dave@[datadyne]:~/$ cat file.txt
Hello Dave, you are 21 years old!
dave@[datadyne]:~/$ bash script.sh >> file.txt
dave@[datadyne]:~/$ cat file.txt
Hello Dave, you are 21 years old!
Hello Dave, you are 21 years old!
This was printed twice because it was appended to the file.
