auparse_first_field - Linux


auparse_first_field extracts the first field from each line of input, based on a specified field delimiter. This is useful for parsing delimited data formats, such as CSV or pipe-separated files, and for extracting specific information from larger text datasets.


auparse_first_field [options] [delimiter]


  • -n, –num-fields (Default: 0): Specify the number of fields to extract from each line. 0 extracts all fields.
  • –regex-delimiter (Default: false): Interpret the delimiter as a regular expression.
  • –case-sensitive (Default: false): Consider case when matching the delimiter.
  • -H, –header (Default: false): Skip the first line and treat it as a header.
  • -h, –help: Display help and exit.
  • -V, –version: Display version information and exit.


Extract the first field from a CSV file with a comma as the delimiter:

$ auparse_first_field input.csv

Extract the first three fields from a pipe-separated file:

$ auparse_first_field -n 3 input.txt |

Extract the first field from a text file, matching any whitespace character as the delimiter:

$ auparse_first_field --regex-delimiter '\s+' input.txt

Common Issues

  • Ensure that the delimiter specified matches the format of your input data.
  • If the input data contains special characters, consider using the --regex-delimiter option to handle them correctly.
  • If the first line of your input is a header, use the --header option to skip it.


auparse_first_field can be combined with other Linux commands to perform complex data manipulation tasks:

  • Chain with cut to extract specific fields by position:
$ auparse_first_field input.csv | cut -d, -f2-4
  • Use with awk to further process extracted fields:
$ auparse_first_field input.txt | 
awk '{print $1+1, $2+2}'

Related Commands

  • cut
  • awk
  • sed