我正在使用以下命令获取管道列表:
lsof | grep PIPE
我想知道FD列中的值代表什么(第五列,http://i.imgur.com/KHczptf.png)。我认为r
和w
分别表示读取和写入,但是这些字符后面跟着的数字是什么意思?
我知道FD代表文件描述符,我想找出列中显示的值的含义,例如3r、16w、20r等。
我正在使用以下命令获取管道列表:
lsof | grep PIPE
我想知道FD列中的值代表什么(第五列,http://i.imgur.com/KHczptf.png)。我认为r
和w
分别表示读取和写入,但是这些字符后面跟着的数字是什么意思?
我知道FD代表文件描述符,我想找出列中显示的值的含义,例如3r、16w、20r等。
文件不仅可以作为流打开。其中一些在lsof
的手册中列出:
文件不只能以流的方式打开,lsof
的手册中还列出了一些其他的打开方式:
FD is the File Descriptor number of the file or:
cwd current working directory;
Lnn library references (AIX);
err FD information error (see NAME column);
jld jail directory (FreeBSD);
ltx shared library text (code and data);
Mxx hex memory-mapped type number xx.
m86 DOS Merge mapped file;
mem memory-mapped file;
mmap memory-mapped device;
pd parent directory;
rtd root directory;
tr kernel trace file (OpenBSD);
txt program text (code and data);
v86 VP/ix mapped file;
FD is followed by one of these characters, describing the
mode under which the file is open:
r for read access;
w for write access;
u for read and write access;
space if mode unknown and no lock
character follows;
'-' if mode unknown and lock
character follows.
The mode character is followed by one of these lock charac-
ters, describing the type of lock applied to the file:
N for a Solaris NFS lock of unknown type;
r for read lock on part of the file;
R for a read lock on the entire file;
w for a write lock on part of the file;
W for a write lock on the entire file;
u for a read and write lock of any length;
U for a lock of unknown type;
x for an SCO OpenServer Xenix lock on part of the
file;
X for an SCO OpenServer Xenix lock on the entire
file;
space if there is no lock.
See the LOCKS section for more information on the lock
information character.
The FD column contents constitutes a single field for pars-
ing in post-processing scripts.
那是文件描述符。
更多信息:
文件描述符(FD)是访问文件的抽象指示器。该术语通常在POSIX操作系统中使用。
在POSIX中,文件描述符是一个整数,具体为C类型int。有三个标准的POSIX文件描述符,对应于三个标准流,每个进程(除了守护进程)都应该期望拥有这些文件描述符。
r
表示只读权限,这意味着文件以只读模式打开,而16只是描述符的数量,没有特殊含义。您可以在路径/proc/PID/fd/FD
中访问该文件,其中PID和FD分别代表进程的pid和描述符号码。 - Igor Chubin