trace the system calls made by a process (and its children)

strace -f -s 512 -v ls -l
strace can be invaluable in trying to figure out what the heck some misbehaving program is doing. There are number of useful flags to limit and control its output, and to attach to already running programs. (See also 'ltrace'.)
Sample Output
23155 execve("/bin/ls", ["ls", "-l"], [/* 40 vars */]) = 0
23155 brk(0)                            = 0x1bad000
23155 mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7faa66e30000
23155 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
23155 mmap(NULL, 8192, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7faa66e2e000
23155 access("/etc/ld.so.preload", R_OK) = -1 ENOENT (No such file or directory)
23155 open("/etc/ld.so.cache", O_RDONLY) = 3
23155 fstat(3, {st_mode=S_IFREG|0644, st_size=119879, ...}) = 0
23155 mmap(NULL, 119879, PROT_READ, MAP_PRIVATE, 3, 0) = 0x7faa66e10000
23155 close(3)                          = 0
23155 access("/etc/ld.so.nohwcap", F_OK) = -1 ENOENT (No such file or directory)
23155 open("/lib/librt.so.1", O_RDONLY) = 3

5
By: mkc
2009-02-06 02:45:33

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