/ system / bin / sh：cat：duty_pcts：I / O错误

Question

linux命令 cat

存在一些问题

#cd /sys/class/leds/green
# ls -al
....
-rw-rw-r-- root    root   4096  1970-01-02 08:00 duty_pcts
....
#cat duty_pctys

此时发生错误

__/system/bin/sh: cat:duty_pcts:I/O error__

Answer 1

cat命令告诉你＆＃34;嘿，我试图读取名为duty_pcts的文件，但由于某种原因，读取失败。我向操作系统询问了errno变量中的错误代码，操作系统告诉我这是一个I / O错误（EIO）。＆＃34;

阅读errno的手册页，打开（2），读取（2）和关闭（2）[例如使用man 2 read]并查看是否有任何系统调用可以将errno设置为EIO。对于read(2)，您会找到例如

   EIO    I/O error. This will happen for example when the process is in
          a background process group, tries to read from its controlling
          tty, and either it is ignoring or blocking SIGTTIN or its pro-
          cess group is orphaned.  It may also occur  when  there  is  a
          low-level I/O error while reading from a disk or tape.