shell – 未生成文件描述符

#!/bin/ksh


var=`ls -lrt /proc/$$/path/0`
echo $var


if [[  -f /proc/$$/path/0 ]]
then
echo "found file descriptor"
else
echo "file descriptor not found"
fi

我在/ tmp /目录中使用示例输入文件对此进行了测试：

$./checkip.sh < /tmp/testip
lrwxrwxrwx 1 root root 0 Dec 31 09:15 /proc/19358/path/0 -> /tmp/testip
found file descriptor

现在我在我们遇到问题的目录中进行了测试.

$./checkip.sh < /var/opt/xxxxxxxx/testip
lrwxrwxrwx 1 root root 0 Dec 31 09:15 /proc/20124/path/0
file descriptor not found
$

我想可能是目录xxxxxxxx.所以我再次使用父目录中的文件对此进行了测试.

$./checkip.sh < /var/opt/testip
lrwxrwxrwx 1 root root 0 Dec 31 09:16 /proc/21286/path/0 -> /var/opt/testip
found file descriptor
$

它再次起作用.但我不认为opt和xxxxxxxx的目录权限之间有任何区别

$ls -l |grep xxxxxxxx
drwxr-xr-x 292 abcdefg   abc         8192 Dec 31 08:33 xxxxxxxx
$cd ..
$ls -l | grep opt
drwxr-xr-x  17 abcdefg   abc          512 Dec 31 09:14 opt

我很困惑为什么没有正确创建0(标准输入)的符号链接.
任何人都可以帮我找到原因吗？

编辑 – 评论

文件不存在

$./checkip.sh < /tmp/notexistfile
/tmp/notexistfile: No such file or directory.

文件已存在

$./checkip.sh < /var/opt/testip
lrwxrwxrwx 1 root root 0 Dec 31 10:49 /proc/15917/path/0 -> /var/opt/testip
found file descriptor

文件已存在

$./checkip.sh < /var/opt/xxxxxxxx/testip
lrwxrwxrwx 1 root root 0 Dec 31 10:49 /proc/16566/path/0
file descriptor not found
$

我可以看到的问题是没有为一个目录创建proc / pid / path / 0中标准输入的符号链接.但可能是什么原因……我没有想法！甚至桁架输出也没有显示如何创建文件(sym link)proc / pid / path / 0.

桁架输出：工作案例(检查stat64调用成功)：

9107/1:          0.0117 read(62,0xFEF687A0,1024)                      = 116
9107/1:            # ! / b i n / k s hnn i f   [ [     - f   / p r o c / $$/ p
9107/1:            a t h / 0   ] ]n t h e nn e c h o   " f o u n d   f i l e   d
9107/1:            e s c r i p t o r "n e l s en e c h o   " f i l e   d e s c r
9107/1:            i p t o r   n o t   f o u n d "n f in
9107/1:          0.0118 sysconfig(6)                                    = 4096
9107/1:          0.0119 stat64(0x0808E630,0x08089B40)                  = 0
9107/1:              0x0808E630: "/proc/9107/path/0"
9107/1:             d=0x04F40002 i=4191608033 m=0100644 l=1  u=308   g=205   sz=3
9107/1:                 at = Dec 31 08:33:06 GMT 2014  [ 1420014786.307569314 ]
9107/1:                 mt = Dec 31 08:33:06 GMT 2014  [ 1420014786.307619723 ]
9107/1:                 ct = Dec 31 08:33:06 GMT 2014  [ 1420014786.307619723 ]
9107/1:             bsz=4096  blks=8     fs=tmpfs

truss输出：不工作情况(检查stat64调用失败)：

10125/1:         0.0057 read(62,1024)                      = 116
10125/1:           # ! / b i n / k s hnn i f   [ [     - f   / p r o c / $$/ p
10125/1:           a t h / 0   ] ]n t h e nn e c h o   " f o u n d   f i l e   d
10125/1:           e s c r i p t o r "n e l s en e c h o   " f i l e   d e s c r
10125/1:           i p t o r   n o t   f o u n d "n f in
10125/1:         0.0058 sysconfig(6)                                    = 4096
10125/1:         0.0071 stat64(0x0808E630,0x08089B40)                  Err#2 ENOENT
10125/1:             0x0808E630: "/proc/10125/path/0"
10125/1:         0.0071 lwp_sigmask(3,0x00020000,0x00000000)          = 0xFFBFFEFF [0x0000FFFF]
10125/1:         0.0071 stat64(0x0808E792,0x08047600)                  Err#2 ENOENT
10125/1:             0x0808E792: "/usr/sbin/echo"
10125/1:         0.0072 lwp_sigmask(3,0x00000000,0x00000000)          = 0xFFBFFEFF [0x0000FFFF]
10125/1:         0.0072 lwp_sigmask(3,0x00000000)          = 0xFFBFFEFF [0x0000FFFF]