gdb log

有时候比如使用gdb的时候
查看help很长，

比如
help  info
可能想grep 很麻烦
虽然gdb可以使用
shell pwd
shell ls
调用系统命令
但是不能用管道和gdb命令交互
所以打印出log 再grep log 比较简单
如下

(gdb) show logging
Future logs will be written to gdb.txt.
Logs will be appended to the log file.
Output will be logged and displayed.
(gdb) set logging file gdb1.txt
(gdb) set logging on
Copying output to gdb.txt.
(gdb) help info
Generic command for showing things about the program being debugged.

List of info subcommands:

info address -- Describe where symbol SYM is stored
info all-registers -- List of all registers and their contents
info args -- Argument variables of current stack frame
...

参考http://stackoverflow.com/questions/7120673/gdb-pipe-output-of-internal-command-to-the-shell-command

help info
help set

info proc 看进程