Hi Michael, thanks for the explanation. Under what circumstances would we use /dev/null and /dev/stderr? For example (let's take assignment as an example here), if i just put "echo" in generating the outputs, why would we still need to use those /dev/..?

I sort of understand the purposes - just not the scenario of when to or when to not use this.

Hi Suan, For example, let's say that the argument to this program is a word $1 being sought in a text $2 if [[ grep $1 $2 > /dev/null ]] then echo "The word: $1 is found in $2" else echo "The word: $1 is not found in $2" fi In this case we don't want all the instances, which are dumped to /dev/null so won't be seen by the user

Alternatively, if you are checking an argument to make sure it's greater than or equal to zero, the error message goes to /dev/stderr, which keeps the error handling away from /dev/stdout (the good stuff). Of course, you are able to combine the two streams if you wish

my_long_running_analysis > results 2>&1 &

This fires off the analysis asynchronously (&) and dumps both stdout and stderr into the file results.

Cheers MichaelW

Cheers MichaelW

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