2.63 对GDB内部命令的输出进行文本处理

https://scz.617.cn/unix/201805152224.txt

Q:

Solaris的mdb、Windows的cdb，其内部命令的输出可以交由外部命令进行文本处理，
比如:

--------------------------------------------------------------------------
<command> ! <shell>

    将mdb命令的输出通过惊叹号转向给外部shell命令，以进一步处理。

<command> | <command>

    将前一条mdb命令的输出做为后一条mdb命令的输入
--------------------------------------------------------------------------

> ::kmem_cache ! egrep vn_cache

> .shell -ci "!peb" findstr ImageFile:

*nix的gdb有无类似能力或变通方案？

A: scz 2023-03-31

高版本gdb内置pipe命令

(gdb) help pipe
pipe, |
Send the output of a gdb command to a shell command.
Usage: | [COMMAND] | SHELL_COMMAND
Usage: | -d DELIM COMMAND DELIM SHELL_COMMAND
Usage: pipe [COMMAND] | SHELL_COMMAND
Usage: pipe -d DELIM COMMAND DELIM SHELL_COMMAND

Executes COMMAND and sends its output to SHELL_COMMAND.

The -d option indicates to use the string DELIM to separate COMMAND
from SHELL_COMMAND, in alternative to |.  This is useful in
case COMMAND contains a | character.

With no COMMAND, repeat the last executed command
and send its output to SHELL_COMMAND.

(gdb) pipe info proc mappings | grep vdso
      0x7ffe2597d000     0x7ffe2597f000     0x2000        0x0  r-xp   [vdso]

(gdb) | info proc mappings | grep vdso
      0x7ffe2597d000     0x7ffe2597f000     0x2000        0x0  r-xp   [vdso]

A: merlin2011 2018-05-15

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

$ vi ShellPipeCommand.py

--------------------------------------------------------------------------
from __future__ import print_function

import gdb
import string
import subprocess
import sys

class ShellPipe ( gdb.Command ):
    "Command to pipe gdb internal command output to external commands."

    def __init__ ( self ) :
        super( ShellPipe, self ).__init__   \
        (
            "shell-pipe",
            gdb.COMMAND_DATA,
            gdb.COMPLETE_NONE,
            True
        )
        gdb.execute( "alias -a sp = shell-pipe", True )

    def invoke ( self, arg, from_tty ) :
        arg     = arg.strip()
        if arg == "" :
            print( "Argument required (gdb_command_and_args | externalcommand..)." )
            return

        gdb_command, shell_commands \
                = None, None

        if '|' in arg :
            #gdb_command, shell_commands = arg.split( "|", maxsplit=1 )
            gdb_command, shell_commands = arg.split( "|", 1 )
            gdb_command, shell_commands = gdb_command.strip(), shell_commands.strip()
        else :
            gdb_command = arg
        #
        # Collect the output and feed it through the pipe
        #
        output  = gdb.execute( gdb_command, True, True )
        if shell_commands :
            shell_process   = subprocess.Popen( shell_commands, stdin=subprocess.PIPE, shell=True )
            shell_process.communicate( output.encode( 'utf-8' ) )
        else:
            sys.stdout.write( output )

ShellPipe()
--------------------------------------------------------------------------

这个脚本过去只能在Python3上跑，小改了一下，现在同时适用于Python2、3。

$ cat /dev/urandom > /dev/null

$ gdb -q -nx -p $(pgrep -ox cat)

(gdb) show version
GNU gdb (Debian 10.1-1.7) 10.1.90.20210103-git

(gdb) python print(sys.version)
3.9.1+ (default, Jan 20 2021, 14:49:22)
[GCC 10.2.1 20210110]

(gdb) source /tmp/ShellPipeCommand.py

或者

$ gdb -q -nx -x /tmp/ShellPipeCommand.py -p $(pgrep -ox cat)

(gdb) sp info proc mappings | grep vdso
        0xb7ef2000 0xb7ef4000     0x2000        0x0 [vdso]

D: scz@nsfocus

不能在GDB之外的Python解释器中直接"import gdb"，会报错:

>>> import gdb
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ModuleNotFoundError: No module named 'gdb'

只能在GDB中导入gdb模块:

(gdb) py import gdb

为了在GDB中导入gdb模块，无需执行:

python3 -m pip install gdb

$ python3 -m pip list | grep gdb
(无输出)