[EMAIL PROTECTED] wrote: > Since I didn't find textutils / coreutils discussion list > (only coreutils-announce), and this is more of a technical > implementation / feature issue, I'm writing this into > bug-textutils. Please forward / repost where appropriate or > let me know.
You have sent your note go a reasonable place. But for the future here is the documentation you were looking for. http://www.gnu.org/software/coreutils/ > Standardize throughout GNU utils (just like long options > have been standardized) a descriptor input / output syntax. In the old days '-' was considered the standard for stdin and stdout. Look at 'tar' for one example. (e.g. 'gunzip file.tar.gz | tar tvf -') But that is "in-band control" and creates the possibility of name conflicts. > e.g. I could write (in bash) something like this : > > ( process1 --output 3>&1 ; process2 --output 4>&1 ) | diff --input-file %3% > --input-file %4% Yes, that is ugly. How about using bash's process substitution? Process Substitution Process substitution is supported on systems that support named pipes (FIFOs) or the /dev/fd method of naming open files. It takes the form of <(list) or >(list). The pro- cess list is run with its input or output connected to a FIFO or some file in /dev/fd. The name of this file is passed as an argument to the current command as the result of the expansion. If the >(list) form is used, writing to the file will provide input for list. If the <(list) form is used, the file passed as an argument should be read to obtain the output of list. Then your above example looks like this. This looks much cleaner to me. diff <(process1) <(process2) Here is a real example you can try. diff -u <(printf "foo\nbar\n") <(printf "baz\nbar\n") --- /tmp/sh-np-a20909 Sat Aug 30 20:59:55 2003 +++ /tmp/sh-np-b20909 Sat Aug 30 20:59:55 2003 @@ -1,2 +1,2 @@ -foo +baz bar This works even on my ancient HP-UX 10.20 machine upon which I tested this example. As long as the system supports named pipes this is available. Newer systems with /dev/fd are even better. But I don't believe this is specified by POSIX and so should be considered a bash only feature. But I say that not knowing if other shells support it or not. Just that it is not a POSIX /bin/sh feature. Bob _______________________________________________ Bug-textutils mailing list [EMAIL PROTECTED] http://mail.gnu.org/mailman/listinfo/bug-textutils
