Summary of common commands based on Linux debugging tools strace and gdb_PHP tutorial

strace and gdb are two commonly used debugging tools in the Linux environment. Here is a personal summary of the common parameters of these two tools during use, which is reserved for future review.
strace debugging tool
The strace tool is used to track system calls and received signals during process execution, including parameters, return values, and execution time. In Linux, if a user program wants to access system devices, it must switch from user mode to kernel mode, which is initiated and completed through system calls.
Strace common parameters:
-c Count the execution time, number of calls, and number of errors for each system call, and give a report when the program exits
-p pid Track the specified process, you can use multiple -p to track multiple processes at the same time
-o filename strace outputs to stdout by default, -o can write the output to the specified file
-f Track generated by fork System calls of sub-processes
-ff Often used with the -o option, system calls generated by different processes (sub-processes) are output to each filename.pid file
-F Try to track vfork sub-process system calls, please note : When used together with -f, vfork will not be traced
-e expr Output filter expression, you can filter out strace results that you do not want to output
-e trace=set Specify the system calls in the trace set
- e trace=network Trace all system calls related to the network
-e strace=signal Trace all system calls related to system signals
-e trace=ipc Trace all system calls related to process communication
- e signal=set Specify the signal in the tracking set
-e read=set Output the data read from the specified file, for example -e read=3,5
-e write=set Output written to the specified file The data in, for example -e write=1
-r　Print the relative time of each system call
-t　Add time information before each line in the output
-tt　Place each line in the output Add time information before each line, the time is accurate to the microsecond level
-ttt Add time information before each line in the output, and the output is relative time
-s Specify the length of each line of output string (default is 32 )
Example of using strace:
strace -t whoami #Trace the whoami executable program and print the execution time before each line of output results
strace -p 17151 -p 17152 -p 17153 #Trace processes 17151, 17152, 17153 at the same time
strace -f -e trace=read,write -p 17151 -o log #Trace the read and write system calls in process 17151 and child processes, output to log file
gdb debugging tool
GDB is a powerful program debugging tool under UNIX released by the GNU open source organization. Adding the -g parameter when compiling gcc can add gdb debugging information to the executable program.
(1) info
Abbreviation: i, lists information about gdb subcommands, such as info break, info variables, info stack, etc.
(2) list [file:]function
Abbreviation: l, view the context of the current line, the default is 10 lines, you can also set the source code to be listed at a certain function.
(3) edit [file:]function
Abbreviation: e, edit the current line or the source code of a function.
(4) break [file:]function
Abbreviation: b, set a breakpoint, which can be set at a certain line or function.
(5) run [arglist]
Abbreviation: r, run the program to the breakpoint and stop. After the run command, you can add the parameters required for debugging the program.
(6) next
Abbreviation: n, single statement execution.
(7) continue
Abbreviation: c, continue running the program to the next breakpoint.
(8) print
Abbreviation: p, prints the value of the variable.
(9) bt
View function stack information.
(10) enter
Enter key to repeat the last debugging command.
(11) help [name]
Displays help information for the specified gdb command.
(12) quit
Abbreviation: q, exit gdb.

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