强大的调试工具 strace
strace是一个优秀的调试工具，它调用的是系统函数ptrace(),缺点是导致应用程序运行的非常慢。
使用
strace -e open target-file
strace -o out ls
# Slow the target command and print details for each syscall:
strace command
# Slow the target PID and print details for each syscall:
strace -p PID
# Slow the target PID and any newly created child process, printing syscall details:
strace -fp PID
# Slow the target PID and record syscalls, printing a summary:
strace -cp PID
# Slow the target PID and trace open() syscalls only:
strace -eopen -p PID
# Slow the target PID and trace open() and stat() syscalls only:
strace -eopen,stat -p PID
# Slow the target PID and trace connect() and accept() syscalls only:
strace -econnect,accept -p PID
# Slow the target command and see what other programs it launches (slow them too!):
strace -qfeexecve command
# Slow the target PID and print time-since-epoch with (distorted) microsecond resolution:
strace -ttt -p PID
# Slow the target PID and print syscall durations with (distorted) microsecond resolution:
strace -T -p PIDsyscall, must to read xx man
read: read bytes from a file descriptor(file,socket)
#include <unistd.h>
ssize_t read(int fd, void *buf, size_t count)
write: write bytes into a file descriptor(file,socket)
open: open a file (return a file descriptor)
close: close a file descriptor.
fork: create a new process(current process is forked)
exec: execute a new program
connect: connect to a network host
accept: accept a network connection
stat: read file statistics
ioctl: set I/O properies, or other miscellaneous functions
mmap: map a file to the process memory address space
brk: extend the heap pointer.