Bash forwarding combined with dual channel designation

Question

Is it possible to combine redirection of output to a file and pipes with ||? (Not sure what it's called)

Example:

(wget -qO- example.com/duff || exit) | some_processing >> outfile.txt 

If wget fails, I would like to exit and not run some_processing or create an empty file.

Answer 1

 #!/bin/bash RESULT=`wget -qO- example.com/duff` if [ $? -eq 0 ]; then echo $RESULT | some_processing >> outfile.txt fi 

Answer 2

|| is logical or. Without creating outfile.txt , a much more complex syntax is required; as you wrote it (in the usual way), outfile.txt is created before wget starts.

I can’t honestly think about how to make the phone not happen at all if the left command does not work. I would just write a Perl script if I were you.

Answer 3

([$? -eq 0] & some_processing → outfile.txt) <<$ (wget -qO- example.com/duff)

Answer 4

I think you pretty much answer how to do this.

If wget fails, I would like to exit and not run some_processing or create an empty file.

---

wget wget -qO- example.com/duff

if [[$? -ne 0]] // $? means return value, on well-written programs it should be zero

then

 some_processing >> outfile.txt 

c

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I think this will accomplish what you want.

Answer 5

Please note that it may not be enough to check the return code. it would also be nice to check the status of the HTTP return, e.g. 404 ..... etc.