GDB basic commands-from opening the file to debugging
Prerequisites
1 gcc-g-o: Compile the original file into a target file that can be debugged by GDB.
2 GDB open the target file to be debugged
3 set ARGs Parameters
Or run.
4. See parameters for show args.
5 show environment view environment
5 unset env clear all environment variables
6 set environment to set an environment variable var1
Set/delete breakpoints
1 info sources or list to view the file. Otherwise, you do not know where to set the breakpoint.
2. view the breakpoint info breakpoints
3 break
4 tbreak: sets a temporary breakpoint and is automatically deleted upon arrival
5 enable
Enable Delete
Enable once
6 disable
7 delete breakpoints delete a breakpoint
Or delete all breakpoints by using delete without adding all parameters.
-> Breakpoint advanced
1 break test. C: 5 set the breakpoint to the specified file
2. Break is paused at a certain position in the memory.
3 break if to set the condition breakpoint
4 condition attach conditions to an existing breakpoint
5. The command can be set at the nth disconnection point.
Start debugging
0. Run the program.
1 step or s single step execution
2 next or N non-entry single-step execution, that is, when other functions are called, they do not enter the function.
3 finish until the function returns
4 until run to a certain row of the Function
5. Execute continue or cont until the next breakpoint or program ends.
6 RETURN modify the program process, directly end the current function, and return the specified value
Set Variables
Set
1 set I = 5 modify the value of a variable in the program
2 set $ I = 5 to set a variable in the PDB environment. This variable is independent from the program, that is, only GDB knows
Get program information
1. Monitoring Variables
Print/FMT print information
FMT Format:
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X hexadecimal
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D decimal
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U unsigned count
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O octal
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T binary
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A hexadecimal print
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C character format
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F floating point number
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2. Tracking Variables
Watch trail assigned action eg. I = 4;
Rwatch follows the read Action eg. B = I;
Awatch tracks all actions
Del watchpoint.
Info display
Display
Show display
Del display
3 monitoring memory
X/
Address can be a memory address or pointer, such as 0x8799f000, P, & VaR
FMT consists of three parts: NFU. N indicates the length to be viewed. U indicates the format, which is divided into bhwg, indicating byte, half word, word, and double word respectively.
.
Eg.
(GDB) x argv [0]
0xbfffff61: 0x6d6f682f
(GDB) x/10cb argv [0]
0xbfffff61: 47 '/'000000' H '000000' 104 'M' 111 'E' 47'/'67 'C' 109 'H'
0xbfffff69: 97 'A' 114 'R'
(GDB) X/10 TB
12
0 x bfffff6b: 01101100 01100101 01110011 00101111
01110111 01101111 01110010 01101011
0xbfff73: 01110000 01101100
(GDB) x/10th
0xbfffff7f:
0110101101101111 0111010000101111 0110000100000000
01100010000000110001100000000 0110010000000000 0110010100000000 0110011000000000
0xbfffff8f: 0110011100000000 0101011000000000
(GDB)
4. view the total frame information
Backtrace or BT
Note: frame is the stack generated when a function is called. It stores information about the function being called.
5. Select the frame to be viewed.
Frame
