Linux 为什么wdiff不能与命名管道一起工作

我怎么能在bash中做到这一点：

$ diff -u <(echo -e "line1\nline2") <(echo -e "line1\nline3")
--- /dev/fd/63  2009-03-30 09:49:07.527272646 +0100
+++ /dev/fd/62  2009-03-30 09:49:07.527272646 +0100
@@ -1,2 +1,2 @@
 line1
-line2
+line3

---

$diff-u我猜wdiff是坏的。
一个
strace
显示
wdiff
stat
s文件（可能是为了找出它们的大小）。由于命名管道报告的大小为0，因此可能假定两个文件都为空，因此相等：

$ strace -efile wdiff -1 <(echo -e "line1\nline2") <(echo -e "line1\nline3")
execve("/usr/bin/wdiff", ["wdiff", "-1", "/dev/fd/63", "/dev/fd/62"], [/* 44 vars */]) = 0
[snip uninteresting stuff]
stat64("/dev/fd/63", {st_mode=S_IFIFO|0600, st_size=0, ...}) = 0
open("/dev/fd/63", O_RDONLY)            = 3
open("/tmp/wdiff.MzPXmH", O_RDWR|O_CREAT|O_EXCL, 0600) = 4
stat64("/dev/fd/62", {st_mode=S_IFIFO|0600, st_size=0, ...}) = 0
open("/dev/fd/62", O_RDONLY)            = 4
open("/tmp/wdiff.5nma9j", O_RDWR|O_CREAT|O_EXCL, 0600) = 5
--- SIGCHLD (Child exited) @ 0 (0) ---
unlink("/tmp/wdiff.MzPXmH")             = 0
unlink("/tmp/wdiff.5nma9j")             = 0
{++}Process 27699 detached
$strace-efile wdiff-1我也可以复制。diff也对文件进行了统计，但仍然有效。有趣的是，这个答案应该被否决，因为被接受的答案证明wdiff确实被破坏了。这可能是因为仅仅声明并没有多大帮助（请注意，我没有投否决票）。
$ strace -efile wdiff -1 <(echo -e "line1\nline2") <(echo -e "line1\nline3")
execve("/usr/bin/wdiff", ["wdiff", "-1", "/dev/fd/63", "/dev/fd/62"], [/* 44 vars */]) = 0
[snip uninteresting stuff]
stat64("/dev/fd/63", {st_mode=S_IFIFO|0600, st_size=0, ...}) = 0
open("/dev/fd/63", O_RDONLY)            = 3
open("/tmp/wdiff.MzPXmH", O_RDWR|O_CREAT|O_EXCL, 0600) = 4
stat64("/dev/fd/62", {st_mode=S_IFIFO|0600, st_size=0, ...}) = 0
open("/dev/fd/62", O_RDONLY)            = 4
open("/tmp/wdiff.5nma9j", O_RDWR|O_CREAT|O_EXCL, 0600) = 5
--- SIGCHLD (Child exited) @ 0 (0) ---
unlink("/tmp/wdiff.MzPXmH")             = 0
unlink("/tmp/wdiff.5nma9j")             = 0
{++}Process 27699 detached