How do I count the files in the HDFS directory?
Your answer
- Use the following commands:
- Total number of files: hadoop fs -ls /path/to/hdfs/* | wc-l.
- Total number of lines: hadoop fs -cat /path/to/hdfs/* | wc-l.
- Total number of lines for a given file: hadoop fs -cat /path/to/hdfs/filename | wc-l.
Table of Contents
How do I list the folders in HDFS?
The following arguments are available with the hadoop ls command: Usage: hadoop fs -ls [-d] [-h] [-R] [-t] [-S] [-r] [-u] Options: -d: Directories are listed as flat files. -h – Formats file sizes in a human-readable way (eg, 64.0 m instead of 67108864). -R: Recursively list the found subdirectories.
Which HDFS command counts the number of file directories and bytes in paths that match the specified file pattern?
Count the number of directories, files, and bytes in paths that match the specified file pattern. Example: hdfs dfs -count hdfs://nn1.example.com/file1 hdfs://nn2.example.com/file2.
How do I list all files in HDFS?
Use the hdfs dfs -ls command to list the files in the Hadoop archives. Run the hdfs dfs -ls command specifying the location of the file directory. Note that the modified main argument causes files to be archived relative to /user/ .
How can I check a file type in HDFS?
use “hdfs dfs -cat /path/to/file | head “,
- for the orc file, the command may print the “ORC” flag on the first line.
- for the parquet file, the command may print the “PAR1” flag on the first line.
- for text file, the command can print the entire content of the file.
Is Hadoop a dfs?
On the other hand, “DFS” refers precisely to access to the Hadoop Distributed File System. So when we use FS it can perform hadoop or local distributed file system related operations and dfs can perform hadoop distributed file system related operations only.
How to write a file to HDFS in Java?
This post demonstrates a Java program to write a file to HDFS using the Hadoop FileSystem API. FileSystem is an abstraction of the file system of which HDFS is an implementation. So you’ll need to get an instance of the FileSystem (HDFS in this case) using the get method. In the program, you can see that the get() method takes the configuration as an argument.
Where are the input and output files in HDFS?
In the above program both input and output files are in HDFS if your input file is in the local file system then you can use BufferedInputStream to create an input stream like here. To run the above Java program in the Hadoop environment, you will need to add the directory that contains the .class file for the Java program to the Hadoop classpath.
How to count number of files in HDFS?
Be careful with getContentSummary#getFileCount(), the same one used by the hdfs dfs -count command: it includes symlinks in the count which can lead to an inaccurate number of files depending on what you need. See github.com/apache/hadoop/blob/… – tozkaOct 27 ’15 at 10:03
How to read a file from HDFS knpcode?
Once it gets the file, the input stream is used to read it, which in HDFS is FSDataInputStream. For the output stream, System.out is used, which prints the data to the console. To run the above program in the Hadoop environment, you will need to add the directory containing the .class file for the Java program to the Hadoop classpath.