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I am little bit confused about redirections in linux.

  1. command > file

  2. command 1> file

  3. command >> file.out 2>> file.err (this is working as expected)

  4. commmand 1>>file.out 2>>file.err (if command is successful , we get output log of command in file.err instead of in file.out

some guys said > and 1> are same but when used with commands not getting proper output.

for example ,

pg_dump -d postgres -t schemaname.table -v -f table.sql   >>table.out 2>>table.err

if I execute above command , if command is successful , it should log the logs to table.log and not in table.err . table.err we get logs only in case pg_dump status exit 1.

My expectation is we get log in table.out when pg_dump executed without any error while dumping tables. and we should get logs in table.err when pg_dump status is exit 1 or it's failed to dump tables.

Thanks!

muru
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Adam Mulla
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    I get right results - please post real command that you use when you get this behaviour. To the other part of your question '>' and '1>' - as I know they are the same. – Damir Oct 22 '21 at 13:54
  • https://wiki.bash-hackers.org/howto/redirection_tutorial will answer all your concerns. – Aaron D. Marasco Oct 22 '21 at 14:33
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    "not getting proper output" ... so, what would the proper output be, in this particular case? What output do you expect to get, and what do you get instead? What does command do? We could explain what >, 1>, >> and 1>> do, and quote the manuals and the standard, but I wonder if it would help more to be able to tie that to your situation. – ilkkachu Oct 22 '21 at 15:33
  • I think you don't understand what stderr is. It's not just for "logs only in case pg_dump status exit 1" - applications are free to use stderr for informational or diagnostic logging, prompts, and other things. – muru Oct 22 '21 at 21:19
  • You need to read a basic book about unix and do the programming samples, at least to some degree. theres all kind of fundamentals that you need to understand to start programming. – john-jones Oct 23 '21 at 11:46

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