1
2
3
4
5
6
7

$ cat file1
1 2 3 4 5 6 7
$ cat file2
1
2
4
3
5
6
7
$ diff <(echo $(< file1)) <(echo $(< file2))
1c1
< 1 2 3 4 5 6 7
---
> 1 2 4 3 5 6 7

< file             # Equivalent to "cat file", but slightly faster since the shell doesn't
                   #     have to fork a new process.

$(< file)          # Capture the output of the "< file" command. Can also be written
                   #     with backticks, as in `< file`.

echo $(< file)     # Echo each word from the file. This will have the side effect of
                   #     collapsing all of the whitespace.

<(echo $(< file))  # An advanced way of piping the output of one command to another.
                   #     The shell opens an unused file descriptor (say fd 42) and pipes
                   #     the echo command to it. Then it passes the filename /dev/fd/42 to
                   #     diff. The result is that you can pipe two different echo commands
                   #     to diff.

$ diff -u <(printf '%sn' $(< file1)) <(printf '%sn' $(< file2))
--- /dev/fd/63  2012-09-10 23:55:30.000000000 -0400
+++ file2   2012-09-10 23:47:24.000000000 -0400
@@ -1,7 +1,7 @@
 1
 2
-3
 4
+3
 5
 6
 7

awk '{printf"%s ", $0}' file2

awk '{for (i=1;i<=NF;i++) printf("%sn", $i)}' file1