我想用strace来查看当我做'hadoop fs -ls'时发生了什么，所以我运行了命令：
strace -f -e trace=execve hadoop fs -ls /stg导致了很多这样的输出：
[pid 187050] execve("/opt/sas/app/platform/lsf/8.0/linux2.6-glibc2.3-x86_64/etc/setsid", ["setsid", "bash", "-c", "echo $$"], [/* 78 vars */]) = -1 ENOENT (No such file or directory) [pid 187050] execve("/opt/sas/app/platform/lsf/8.0/linux2.6-glibc2.3-x86_64/bin/setsid", ["setsid", "bash", "-c", "echo $$"], [/* 78 vars */]) = -1 ENOENT (No such file or directory) [pid 187050] execve("/opt/dca/bin/setsid", ["setsid", "bash", "-c", "echo $$"], [/* 78 vars */]) = -1 ENOENT (No such file or directory) [pid 187050] execve("/usr/local/greenplum-cc-web/./bin/setsid", ["setsid", "bash", "-c", "echo $$"], [/* 78 vars */]) = -1 ENOENT (No such file or directory) [pid 187050] execve("/usr/lib64/qt-3.3/bin/setsid", ["setsid", "bash", "-c", "echo $$"], [/* 78 vars */]) = -1 ENOENT (No such file or directory) [pid 187050] execve("/usr/local/bin/setsid", ["setsid", "bash", "-c", "echo $$"], [/* 78 vars */]) = -1 ENOENT (No such file or directory) [pid 187050] execve("/bin/setsid", ["setsid", "bash", "-c", "echo $$"], [/* 78 vars */]) = -1 ENOENT (No such file or directory) [pid 187050] execve("/usr/bin/setsid", ["setsid", "bash", "-c", "echo $$"], [/* 78 vars */]) = 0
为什么会有这么多-1 ENOENT (No such file or directory)结果？
它试图通过调用$PATH每个潜在位置来运行程序，而不必预知程序在哪里。 这是完全正常的，因为在很多软件商店中，通过执行诸如stat() execve()被认为是安全最佳实践的竞争条件。