Extract matches with a regular expression

Bash

grep -o prints only the matching part, which turns grep into a crude extractor.

grep -oE '[0-9]{1,3}(\.[0-9]{1,3}){3}' access.log | sort -u

# Every email address in a directory:
grep -rhoE '[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}' . | sort -u

Download

Text Processing grep regex extraction chris

More in Text Processing

Rewrite a CSV column with perl Text Processing A one-liner that upper-cases the second field of every row, leaving the rest alone. Sort and deduplicate lines by a field Text Processing Sorts on the second column and keeps the first row of each group. Replace text across a whole project Text Processing ripgrep finds the files, sed edits them in place. The dry run first is not optional. Sum a column with awk Text Processing Adds the third field of every line and prints the total, ignoring anything non-numeric. Pretty-print and query JSON Text Processing jq for the common cases: reformat, pick a path, filter an array, and reshape. A regular expression for ISO 8601 dates Text Processing Matches a date, optionally with a time and a zone. Deliberately strict about separators.

Random picks

Watch a command until it succeeds Shell Retries every two seconds and stops the moment the command exits zero. Useful while waiting for a service to come up. Parse arguments without a dependency Python argparse covers subcommands, types and help text, which is more than most scripts ever need. A semantic, accessible form field Web & CSS The label is tied to the input by id, and the hint is announced with it via aria-describedby. A dataclass with validation Python __post_init__ runs after the generated constructor, which is where cheap invariants belong. Shell into a running container Containers Falls back to sh, since slim images often have no bash. A test that fails for the right reason Testing Assert on the message, not merely that something threw. A typo raising TypeError would otherwise pass. Generate an SSH key and add it to the agent Security Ed25519 rather than RSA: shorter, faster, and no key-size decision to get wrong. Group an array by a key JavaScript Object.groupBy is available in current runtimes; the reduce version is the fallback for older ones.