Package org.apache.zookeeper
Class Shell
- java.lang.Object
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- org.apache.zookeeper.Shell
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- Direct Known Subclasses:
Shell.ShellCommandExecutor
public abstract class Shell extends Object
A base class for running a Unix command.Shellcan be used to run unix commands likeduordf. It also offers facilities to gate commands by time-intervals.
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Nested Class Summary
Nested Classes Modifier and Type Class Description static classShell.ExitCodeExceptionThis is an IOException with exit code added.static classShell.ShellCommandExecutorA simple shell command executor.
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Field Summary
Fields Modifier and Type Field Description static StringSET_GROUP_COMMANDstatic StringSET_OWNER_COMMANDa Unix command to set ownerstatic StringSET_PERMISSION_COMMANDa Unix command to set permissionprotected longtimeOutIntervalTime after which the executing script would be timedoutstatic StringULIMIT_COMMANDa Unix command to get ulimit of a process.static StringUSER_NAME_COMMANDa Unix command to get the current user's namestatic booleanWINDOWSSet to true on Windows platforms
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Method Summary
All Methods Static Methods Instance Methods Abstract Methods Concrete Methods Modifier and Type Method Description static StringexecCommand(String... cmd)Static method to execute a shell command.static StringexecCommand(Map<String,String> env, String... cmd)Static method to execute a shell command.static StringexecCommand(Map<String,String> env, String[] cmd, long timeout)Static method to execute a shell command.protected abstract String[]getExecString()return an array containing the command name and its parametersintgetExitCode()get the exit codestatic String[]getGET_PERMISSION_COMMAND()Return a Unix command to get permission information.static String[]getGroupsCommand()a Unix command to get the current user's groups liststatic String[]getGroupsForUserCommand(String user)a Unix command to get a given user's groups listProcessgetProcess()get the current sub-process executing the given commandstatic String[]getUlimitMemoryCommand(int memoryLimit)Get the Unix command for setting the maximum virtual memory available to a given child process.booleanisTimedOut()To check if the passed script to shell command executor timed out or not.protected abstract voidparseExecResult(BufferedReader lines)Parse the execution resultprotected voidrun()check to see if a command needs to be executed and execute if neededprotected voidsetEnvironment(Map<String,String> env)set the environment for the commandprotected voidsetWorkingDirectory(File dir)set the working directory
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Field Detail
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USER_NAME_COMMAND
public static final String USER_NAME_COMMAND
a Unix command to get the current user's name- See Also:
- Constant Field Values
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SET_PERMISSION_COMMAND
public static final String SET_PERMISSION_COMMAND
a Unix command to set permission- See Also:
- Constant Field Values
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SET_OWNER_COMMAND
public static final String SET_OWNER_COMMAND
a Unix command to set owner- See Also:
- Constant Field Values
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SET_GROUP_COMMAND
public static final String SET_GROUP_COMMAND
- See Also:
- Constant Field Values
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timeOutInterval
protected long timeOutInterval
Time after which the executing script would be timedout
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ULIMIT_COMMAND
public static final String ULIMIT_COMMAND
a Unix command to get ulimit of a process.- See Also:
- Constant Field Values
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WINDOWS
public static final boolean WINDOWS
Set to true on Windows platforms
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Method Detail
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getGroupsCommand
public static String[] getGroupsCommand()
a Unix command to get the current user's groups list
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getGroupsForUserCommand
public static String[] getGroupsForUserCommand(String user)
a Unix command to get a given user's groups list
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getGET_PERMISSION_COMMAND
public static String[] getGET_PERMISSION_COMMAND()
Return a Unix command to get permission information.
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getUlimitMemoryCommand
public static String[] getUlimitMemoryCommand(int memoryLimit)
Get the Unix command for setting the maximum virtual memory available to a given child process. This is only relevant when we are forking a process from within the Mapper or the Reducer implementations. Also see Hadoop Pipes and Hadoop Streaming. It also checks to ensure that we are running on a *nix platform else (e.g. in Cygwin/Windows) it returnsnull.- Parameters:
memoryLimit- virtual memory limit- Returns:
- a
String[]with the ulimit command arguments ornullif we are running on a non *nix platform or if the limit is unspecified.
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setEnvironment
protected void setEnvironment(Map<String,String> env)
set the environment for the command- Parameters:
env- Mapping of environment variables
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setWorkingDirectory
protected void setWorkingDirectory(File dir)
set the working directory- Parameters:
dir- The directory where the command would be executed
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run
protected void run() throws IOExceptioncheck to see if a command needs to be executed and execute if needed- Throws:
IOException
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getExecString
protected abstract String[] getExecString()
return an array containing the command name and its parameters
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parseExecResult
protected abstract void parseExecResult(BufferedReader lines) throws IOException
Parse the execution result- Throws:
IOException
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getProcess
public Process getProcess()
get the current sub-process executing the given command- Returns:
- process executing the command
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getExitCode
public int getExitCode()
get the exit code- Returns:
- the exit code of the process
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isTimedOut
public boolean isTimedOut()
To check if the passed script to shell command executor timed out or not.- Returns:
- if the script timed out.
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execCommand
public static String execCommand(String... cmd) throws IOException
Static method to execute a shell command. Covers most of the simple cases without requiring the user to implement theShellinterface.- Parameters:
cmd- shell command to execute.- Returns:
- the output of the executed command.
- Throws:
IOException
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execCommand
public static String execCommand(Map<String,String> env, String[] cmd, long timeout) throws IOException
Static method to execute a shell command. Covers most of the simple cases without requiring the user to implement theShellinterface.- Parameters:
env- the map of environment key=valuecmd- shell command to execute.timeout- time in milliseconds after which script should be marked timeout- Returns:
- the output of the executed command.o
- Throws:
IOException
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execCommand
public static String execCommand(Map<String,String> env, String... cmd) throws IOException
Static method to execute a shell command. Covers most of the simple cases without requiring the user to implement theShellinterface.- Parameters:
env- the map of environment key=valuecmd- shell command to execute.- Returns:
- the output of the executed command.
- Throws:
IOException
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