public abstract class Shell extends Object
Shell
can be used to run unix commands like du
or
df
. It also offers facilities to gate commands by
time-intervals.Modifier and Type | Class and Description |
---|---|
static class |
Shell.ExitCodeException
This is an IOException with exit code added.
|
static class |
Shell.ShellCommandExecutor
A simple shell command executor.
|
Modifier and Type | Field and Description |
---|---|
static org.apache.commons.logging.Log |
LOG |
static String |
SET_GROUP_COMMAND |
static String |
SET_OWNER_COMMAND
a Unix command to set owner
|
static String |
SET_PERMISSION_COMMAND
a Unix command to set permission
|
static String |
USER_NAME_COMMAND
a Unix command to get the current user's name
|
static boolean |
WINDOWS
Set to true on Windows platforms
|
Modifier and Type | Method and Description |
---|---|
static String |
execCommand(Map<String,String> env,
String... cmd)
Static method to execute a shell command.
|
static String |
execCommand(String... cmd)
Static method to execute a shell command.
|
protected abstract String[] |
getExecString()
return an array containing the command name & its parameters
|
int |
getExitCode()
get the exit code
|
static String[] |
getGET_PERMISSION_COMMAND()
Return a Unix command to get permission information.
|
static String[] |
getGROUPS_COMMAND()
a Unix command to get the current user's groups list
|
Process |
getProcess()
get the current sub-process executing the given command
|
static String[] |
getUlimitMemoryCommand(Configuration conf)
Get the Unix command for setting the maximum virtual memory available
to a given child process.
|
protected abstract void |
parseExecResult(BufferedReader lines)
Parse the execution result
|
protected void |
run()
check to see if a command needs to be executed and execute if needed
|
protected void |
setEnvironment(Map<String,String> env)
set the environment for the command
|
protected void |
setWorkingDirectory(File dir)
set the working directory
|
public static final org.apache.commons.logging.Log LOG
public static final String USER_NAME_COMMAND
public static final String SET_PERMISSION_COMMAND
public static final String SET_OWNER_COMMAND
public static final String SET_GROUP_COMMAND
public static final boolean WINDOWS
public Shell()
public Shell(long interval)
interval
- the minimum duration to wait before re-executing the
command.public static String[] getGROUPS_COMMAND()
public static String[] getGET_PERMISSION_COMMAND()
public static String[] getUlimitMemoryCommand(Configuration conf)
Mapper
or the
Reducer
implementations
e.g. Hadoop Pipes
or Hadoop Streaming.
It also checks to ensure that we are running on a *nix platform else
(e.g. in Cygwin/Windows) it returns null
.conf
- configurationString[]
with the ulimit command arguments or
null
if we are running on a non *nix platform or
if the limit is unspecified.protected void setEnvironment(Map<String,String> env)
env
- Mapping of environment variablesprotected void setWorkingDirectory(File dir)
dir
- The directory where the command would be executedprotected void run() throws IOException
IOException
protected abstract String[] getExecString()
protected abstract void parseExecResult(BufferedReader lines) throws IOException
IOException
public Process getProcess()
public int getExitCode()
public static String execCommand(String... cmd) throws IOException
Shell
interface.cmd
- shell command to execute.IOException
public static String execCommand(Map<String,String> env, String... cmd) throws IOException
Shell
interface.env
- the map of environment key=valuecmd
- shell command to execute.IOException
Copyright © 2010 The Apache Software Foundation