# 得到命令的幫助信息 ## 技巧 使用`help`命令可以得到gdb的命令幫助信息： （1）`help`命令不加任何參數會得到命令的分類： (gdb) help List of classes of commands: aliases -- Aliases of other commands breakpoints -- Making program stop at certain points data -- Examining data files -- Specifying and examining files internals -- Maintenance commands obscure -- Obscure features running -- Running the program stack -- Examining the stack status -- Status inquiries support -- Support facilities tracepoints -- Tracing of program execution without stopping the program user-defined -- User-defined commands Type "help" followed by a class name for a list of commands in that class. Type "help all" for the list of all commands. Type "help" followed by command name for full documentation. Type "apropos word" to search for commands related to "word". Command name abbreviations are allowed if unambiguous. （2）當輸入`help class`命令時，可以得到這個類別下所有命令的列表和命令功能： (gdb) help data Examining data. List of commands: append -- Append target code/data to a local file append binary -- Append target code/data to a raw binary file append binary memory -- Append contents of memory to a raw binary file append binary value -- Append the value of an expression to a raw binary file append memory -- Append contents of memory to a raw binary file append value -- Append the value of an expression to a raw binary file call -- Call a function in the program disassemble -- Disassemble a specified section of memory display -- Print value of expression EXP each time the program stops dump -- Dump target code/data to a local file dump binary -- Write target code/data to a raw binary file dump binary memory -- Write contents of memory to a raw binary file dump binary value -- Write the value of an expression to a raw binary file ...... （3）也可以用`help command`命令得到某一個具體命令的用法： (gdb) help mem Define attributes for memory region or reset memory region handling totarget-based. Usage: mem auto mem <lo addr> <hi addr> [<mode> <width> <cache>], where <mode> may be rw (read/write), ro (read-only) or wo (write-only), <width> may be 8, 16, 32, or 64, and <cache> may be cache or nocache （4）用`apropos regexp`命令查找所有符合`regexp`正則表達式的命令信息： (gdb) apropos set awatch -- Set a watchpoint for an expression b -- Set breakpoint at specified line or function br -- Set breakpoint at specified line or function bre -- Set breakpoint at specified line or function brea -- Set breakpoint at specified line or function ...... 詳情參見[gdb手冊](https://sourceware.org/gdb/onlinedocs/gdb/Help.html) ## 貢獻者 nanxiao