uudecode - Linux


uudecode is a command-line utility used primarily for decoding files encoded using the uuencode method. This encoding technique was historically used to convert binary data into ASCII text so that it could be safely transmitted over networks that only supported text data. The uudecode command reverses this process, reconstructing the original binary file from the encoded ASCII text. It is commonly utilized in email transfers and newsgroup communications.


The basic syntax for uudecode is as follows:

uudecode [options] [file]
  • file: This is the optional input file to decode. If no file is specified, uudecode reads from the standard input.


The following options are supported by uudecode:

  • -o file, --output-file=file: Directs uudecode to write the output to file instead of the default filename specified in the encoded file’s header.
  • -p, --stdout: Write output to standard output (stdout), allowing for further processing through piping to other commands.
  • -c: Instead of writing the encoded file, specify the encoded mode (permissions) without prompting for overwrite.
  • -v, --version: Display version information and exit.
  • -h, --help: Display a help message and exit.


  1. Basic Decoding:
    Decode a file named encoded.txt and output the original file as defined in its header.

    uudecode encoded.txt
  2. Decoding to Standard Output:
    Decode and output the content directly to the terminal or to be piped into another command:

    uudecode -p encoded.txt | less
  3. Specifying Output Filename:
    Decode encoded.txt and save the output to a specific file named output.zip:

    uudecode -o output.zip encoded.txt

Common Issues

  • Missing Input File: If the input file is missing or corrupted, uudecode will fail with an error stating it cannot read the file. Ensure the file exists and is accessible.
  • Permission Errors: Problems may occur if the output file cannot be written. Check that you have write permissions in the directory.
  • Incorrect Encoding: If the file was not correctly uuencoded, uudecode will not be able to decode it properly. Verify the integrity and source of the encoded file.


uudecode can be combined with other tools for script-based file handling or data processing. For example, decoding multiple files in a directory, and processing them through a script:

for file in *.uu; do
    uudecode "$file" -o "${file%.uu}"

This loop will decode all .uu files in the current directory to their original formats.

  • uuencode: Encodes a binary file into text format.
  • base64: Similar to uuencode and uudecode but uses Base64 encoding.
  • curl or wget: These commands might be used to download uuencoded files from the internet.

For further reading, you can refer to the official documentation usually available on Linux distributions via the man command, e.g., man uudecode.