field_userptr - Linux


The field_userptr command is a powerful tool used to carry out various string field manipulations, enabling users to modify and extract specific strings based on specified parameters. It finds its primary application in scripts and tools that require precise string manipulation capabilities.


field_userptr [-l list] [-u userptr] [-s string] [-b base] [-o output] [-d delim] [-a append] [-r replace] [-i] [-e] [-v] [-h] file


  • -l list: Specify a list of fields to extract.
  • -u userptr: Define the user-provided pointer for field manipulation.
  • -s string: Provide the string to search for or manipulate.
  • -b base: Set the base address for field modification.
  • -o output: Specify the output file for modified data.
  • -d delim: Use a delimiter to separate fields. Default is comma (,).
  • -a append: Append the modified string to the field.
  • -r replace: Replace the existing string with the modified string.
  • -i: Perform case-insensitive search.
  • -e: Exit after the first match.
  • -v: Activate verbose mode for detailed output.
  • -h: Display help information.


1. Extract a specific field:

field_userptr -l field2 file.txt

2. Modify a field and save the result:

field_userptr -l field3 -s "updated_data" -a file.txt -o modified.txt

Common Issues

1. Field not found: Ensure the specified field exists in the input file.

2. Incorrect syntax: Carefully check the command syntax for any typos or missing arguments.


1. Combine with grep:

cat file.txt | field_userptr -l field2 | grep "value"

2. Use as part of a script:


FILES=$(find . -name "*.txt")
for FILE in $FILES; do
  field_userptr -l field3 -u userptr -a $FILE

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