Flume :Exec source cat command is not writing on HDFS

i'm trying to write data into Hdfs using Flume-ng for exec source.But it always ended with exit code 127.and it's also showing warning like

Unable to get maxDirectMemory from VM: NoSuchMethodException: sun.misc.VM.maxDirectMemory(null).

This is exec.conf file

execAgent.sources=e
execAgent.channels=memchannel
execAgent.sinks=HDFS
execAgent.sources.e.type=org.apache.flume.source.ExecSource
execAgent.sources.e.channels=memchannel
execAgent.sources.e.shell=/bin/bash
execAgent.sources.e.command=tail -f /home/sample.txt
execAgent.sinks.HDFS.type=hdfs
execAgent.sinks.HDFS.channel=memchannel
execAgent.sinks.HDFS.hdfs.path=hdfs://ip:address:port/user/flume/
execAgent.sinks.HDFS.hdfs.fileType=DataStream
execAgent.sinks.HDFS.hdfs.writeFormat=Text
execAgent.channels.memchannel.type=file
execAgent.channels.memchannel.capacity=1000
execAgent.channels.memchannel.transactionCapacity=100
execAgent.sources.e.channels=memchannel
execAgent.sinks.HDFS.channel=memchannel

this is the output i'm getting on console

15/04/17 06:24:54 INFO node.PollingPropertiesFileConfigurationProvider: Configuration provider starting
15/04/17 06:24:54 INFO node.PollingPropertiesFileConfigurationProvider: Reloading configuration file:exec.conf
15/04/17 06:24:54 INFO conf.FlumeConfiguration: Processing:HDFS
15/04/17 06:24:54 INFO conf.FlumeConfiguration: Processing:HDFS
15/04/17 06:24:54 INFO conf.FlumeConfiguration: Processing:HDFS
15/04/17 06:24:54 INFO conf.FlumeConfiguration: Added sinks: HDFS Agent: execAgent
15/04/17 06:24:54 INFO conf.FlumeConfiguration: Processing:HDFS
15/04/17 06:24:54 INFO conf.FlumeConfiguration: Processing:HDFS
15/04/17 06:24:55 INFO conf.FlumeConfiguration: Post-validation flume configuration contains configuration for agents: [execAgent]
15/04/17 06:24:55 INFO node.AbstractConfigurationProvider: Creating channels
15/04/17 06:24:55 INFO channel.DefaultChannelFactory: Creating instance of channel memchannel type file
15/04/17 06:24:55 INFO node.AbstractConfigurationProvider: Created channel memchannel
15/04/17 06:24:55 INFO source.DefaultSourceFactory: Creating instance of source e, type org.apache.flume.source.ExecSource
15/04/17 06:24:55 INFO sink.DefaultSinkFactory: Creating instance of sink: HDFS, type: hdfs
15/04/17 06:24:56 INFO hdfs.HDFSEventSink: Hadoop Security enabled: false
15/04/17 06:24:56 INFO node.AbstractConfigurationProvider: Channel memchannel connected to [e, HDFS]
15/04/17 06:24:56 INFO node.Application: Starting new configuration:{ sourceRunners:{e=EventDrivenSourceRunner: { source:org.apache.flume.source.ExecSource{name:e,state:IDLE} }} sinkRunners:{HDFS=SinkRunner: { policy:org.apache.flume.sink.DefaultSinkProcessor@2577d2c2 counterGroup:{ name:null counters:{} } }} channels:{memchannel=FileChannel memchannel { dataDirs: [/root/.flume/file-channel/data] }} }
15/04/17 06:24:56 INFO node.Application: Starting Channel memchannel
15/04/17 06:24:56 INFO file.FileChannel: Starting FileChannel memchannel { dataDirs: [/root/.flume/file-channel/data] }...
15/04/17 06:24:56 INFO file.Log: Encryption is not enabled
15/04/17 06:24:56 INFO file.Log: Replay started
15/04/17 06:24:56 INFO file.Log: Found NextFileID 0, from []
15/04/17 06:24:56 INFO file.EventQueueBackingStoreFile: Preallocated /root/.flume/file-channel/checkpoint/checkpoint_1429251896225 to 16232 for capacity 1000
15/04/17 06:24:56 INFO file.EventQueueBackingStoreFileV3: Starting up with /root/.flume/file-channel/checkpoint/checkpoint_1429251896225 and /root/.flume/file-channel/checkpoint/checkpoint_1429251896225.meta
15/04/17 06:24:57 INFO file.Log: Last Checkpoint Fri Apr 17 06:24:56 UTC 2015, queue depth = 0
15/04/17 06:24:57 INFO file.Log: Replaying logs with v2 replay logic
15/04/17 06:24:57 INFO file.ReplayHandler: Starting replay of []
15/04/17 06:24:57 INFO file.ReplayHandler: read: 0, put: 0, take: 0, rollback: 0, commit: 0, skip: 0, eventCount:0
15/04/17 06:24:57 INFO file.Log: Rolling /root/.flume/file-channel/data
15/04/17 06:24:57 INFO file.Log: Roll start /root/.flume/file-channel/data
15/04/17 06:24:57 INFO tools.DirectMemoryUtils: Unable to get maxDirectMemory from VM: NoSuchMethodException: sun.misc.VM.maxDirectMemory(null)
15/04/17 06:24:57 INFO tools.DirectMemoryUtils: Direct Memory Allocation:  Allocation = 1048576, Allocated = 0, MaxDirectMemorySize = 18874368, Remaining = 18874368
15/04/17 06:24:57 INFO file.LogFile: Opened /root/.flume/file-channel/data/log-1
15/04/17 06:24:57 INFO file.Log: Roll end
15/04/17 06:24:57 INFO file.EventQueueBackingStoreFile: Start checkpoint for /root/.flume/file-channel/checkpoint/checkpoint_1429251896225, elements to sync = 0
15/04/17 06:24:57 INFO file.EventQueueBackingStoreFile: Updating checkpoint metadata: logWriteOrderID: 1429251897136, queueSize: 0, queueHead: 0
15/04/17 06:24:57 INFO file.Log: Updated checkpoint for file: /root/.flume/file-channel/data/log-1 position: 0 logWriteOrderID: 1429251897136
15/04/17 06:24:57 INFO file.FileChannel: Queue Size after replay: 0 [channel=memchannel]
15/04/17 06:24:57 INFO instrumentation.MonitoredCounterGroup: Monitoried counter group for type: CHANNEL, name: memchannel, registered successfully.
15/04/17 06:24:57 INFO instrumentation.MonitoredCounterGroup: Component type: CHANNEL, name: memchannel started
15/04/17 06:24:57 INFO node.Application: Starting Sink HDFS
15/04/17 06:24:57 INFO node.Application: Starting Source e
15/04/17 06:24:57 INFO source.ExecSource: Exec source starting with command:tail -f /home/sample.txt
15/04/17 06:24:57 INFO instrumentation.MonitoredCounterGroup: Monitoried counter group for type: SINK, name: HDFS, registered successfully.
15/04/17 06:24:57 INFO instrumentation.MonitoredCounterGroup: Component type: SINK, name: HDFS started
15/04/17 06:24:57 INFO instrumentation.MonitoredCounterGroup: Monitoried counter group for type: SOURCE, name: e, registered successfully.
15/04/17 06:24:57 INFO instrumentation.MonitoredCounterGroup: Component type: SOURCE, name: e started
15/04/17 06:24:57 INFO source.ExecSource: Command [tail -f /home/brillio/sample.txt] exited with 127