Merge pull request #97389 from dagiro/freshness78

freshness78

Author: PRMerger8

articles/hdinsight/hdinsight-hadoop-script-actions-linux.md

@@ -6,7 +6,7 @@ ms.author: hrasheed
 ms.reviewer: jasonh
 ms.service: hdinsight
 ms.topic: conceptual
-ms.date: 04/22/2019
+ms.date: 11/28/2019
 ---
 
 # Script action development with HDInsight
@@ -70,7 +70,7 @@ fi
 
 ### <a name="bps10"></a> Target the operating system version
 
-Linux-based HDInsight is based on the Ubuntu Linux distribution. Different versions of HDInsight rely on different versions of Ubuntu, which may change how your script behaves. For example, HDInsight 3.4 and earlier are based on Ubuntu versions that use Upstart. Versions 3.5 and greater are based on Ubuntu 16.04, which uses Systemd. Systemd and Upstart rely on different commands, so your script should be written to work with both.
+HDInsight is based on the Ubuntu Linux distribution. Different versions of HDInsight rely on different versions of Ubuntu, which may change how your script behaves. For example, HDInsight 3.4 and earlier are based on Ubuntu versions that use Upstart. Versions 3.5 and greater are based on Ubuntu 16.04, which uses Systemd. Systemd and Upstart rely on different commands, so your script should be written to work with both.
 
 Another important difference between HDInsight 3.4 and 3.5 is that `JAVA_HOME` now points to Java 8. The following code demonstrates how to determine if the script is running on Ubuntu 14 or 16:
 
@@ -128,11 +128,11 @@ To reduce the time it takes to run the script, avoid operations that compile res
 
 Scripts must be idempotent. If the script runs multiple times, it should return the cluster to the same state every time.
 
-For example, a script that modifies configuration files should not add duplicate entries if ran multiple times.
+For example, a script that modifies configuration files shouldn't add duplicate entries if ran multiple times.
 
 ### <a name="bPS5"></a>Ensure high availability of the cluster architecture
 
-Linux-based HDInsight clusters provide two head nodes that are active within the cluster, and script actions run on both nodes. If the components you install expect only one head node, do not install the components on both head nodes.
+Linux-based HDInsight clusters provide two head nodes that are active within the cluster, and script actions run on both nodes. If the components you install expect only one head node, don't install the components on both head nodes.
 
 > [!IMPORTANT]  
 > Services provided as part of HDInsight are designed to fail over between the two head nodes as needed. This functionality is not extended to custom components installed through script actions. If you need high availability for custom components, you must implement your own failover mechanism.
@@ -141,7 +141,7 @@ Linux-based HDInsight clusters provide two head nodes that are active within the
 
 Components that you install on the cluster might have a default configuration that uses Apache Hadoop Distributed File System (HDFS) storage. HDInsight uses either Azure Storage or Data Lake Storage as the default storage. Both provide an HDFS compatible file system that persists data even if the cluster is deleted. You may need to configure components you install to use WASB or ADL instead of HDFS.
 
-For most operations, you do not need to specify the file system. For example, the following copies the hadoop-common.jar file from the local file system to cluster storage:
+For most operations, you don't need to specify the file system. For example, the following copies the hadoop-common.jar file from the local file system to cluster storage:
 
 ```bash
 hdfs dfs -put /usr/hdp/current/hadoop-client/hadoop-common.jar /example/jars/
@@ -183,7 +183,7 @@ line 1: #!/usr/bin/env: No such file or directory
 
 ### <a name="bps9"></a> Use retry logic to recover from transient errors
 
-When downloading files, installing packages using apt-get, or other actions that transmit data over the internet, the action may fail due to transient networking errors. For example, the remote resource you are communicating with may be in the process of failing over to a backup node.
+When downloading files, installing packages using apt-get, or other actions that transmit data over the internet, the action may fail because of transient networking errors. For example, the remote resource you're communicating with may be in the process of failing over to a backup node.
 
 To make your script resilient to transient errors, you can implement retry logic. The following function demonstrates how to implement retry logic. It retries the operation three times before failing.
 
@@ -232,7 +232,7 @@ The following helpers available for use in your script:
 
 | Helper usage | Description |
 | --- | --- |
-| `download_file SOURCEURL DESTFILEPATH [OVERWRITE]` |Downloads a file from the source URI to the specified file path. By default, it does not overwrite an existing file. |
+| `download_file SOURCEURL DESTFILEPATH [OVERWRITE]` |Downloads a file from the source URI to the specified file path. By default, it doesn't overwrite an existing file. |
 | `untar_file TARFILE DESTDIR` |Extracts a tar file (using `-xf`) to the destination directory. |
 | `test_is_headnode` |If ran on a cluster head node, return 1; otherwise, 0. |
 | `test_is_datanode` |If the current node is a data (worker) node, return a 1; otherwise, 0. |
@@ -324,15 +324,15 @@ Microsoft provides sample scripts to install components on an HDInsight cluster.
 
 ## Troubleshooting
 
-The following are errors you may encounter when using scripts you have developed:
+The following are errors you may come across when using scripts you've developed:
 
 **Error**: `$'\r': command not found`. Sometimes followed by `syntax error: unexpected end of file`.
 
 *Cause*: This error is caused when the lines in a script end with CRLF. Unix systems expect only LF as the line ending.
 
 This problem most often occurs when the script is authored on a Windows environment, as CRLF is a common line ending for many text editors on Windows.
 
-*Resolution*: If it is an option in your text editor, select Unix format or LF for the line ending. You may also use the following commands on a Unix system to change the CRLF to an LF:
+*Resolution*: If it's an option in your text editor, select Unix format or LF for the line ending. You may also use the following commands on a Unix system to change the CRLF to an LF:
 
 > [!NOTE]  
 > The following commands are roughly equivalent in that they should change the CRLF line endings to LF. Select one based on the utilities available on your system.