Say I have too programs a and b that I can run with ./a and ./b.
Is it possible to diff their outputs without first writing to temporary files?
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87answers:
2
+12
A:
Use <(command) to pass one command's output to another program as if it were a file name. Bash pipes the program's output to a pipe and passes a file name like /dev/fd/63 to the outer command.
diff <(./a) <(./b)
Similarly you can use >(command) if you want to pipe something into a command.
John Kugelman
2010-09-26 23:06:16
One drawback to be aware of is that if ./a or ./b fails, the caller will not find that out.
Alexander Pogrebnyak
2010-09-26 23:19:15
The OP did tag the question bash, but for the record, this doesn't work in any other shell. It's a bash extension to the Posix utility standard.
DigitalRoss
2010-09-27 00:46:03
+2
A:
One options would be to use named pipes (FIFOs):
mkfifo a_fifo b_fifo
./a > a_fifo &
./b > b_fifo &
diff a_fifo b_fifo
... but John Kugelman's solution is much cleaner.
martin clayton
2010-09-26 23:11:37