excavate

A command line tool to excavate columns from multi-column texts.

excavate is a simple program that does one specific job, getting and printing the specified column, line-by-line reading from standard input. This is a job that can be done by some more sophisticated programs, e.g. awk or sed, but having the memory capacity of a goldfish, I never could recall their syntax when I need to. Personally, I frequently need the fetching of a column, and infrequently need anything that requires the rich feature-set offered by those tools. That's my rationale for creating this highly specialized, simplistic, one-trick-pony program.

Usage:

excavate <COLUMNS>

<COLUMNS> is supplied in the format of comma delimited list. Each item can be a positive integer, or a range in the format of "a-b". At least one column must be specified. The column ID starts from 0 (first column is 0, the second 1, etc.). The range "a-b" includes both end, with "a" being the lower end, and "b" the higher end. If "a" is greater than "b", the range is empty (selects no column).

For example:

For example:

Printing the all the process IDs matching "bash":

$ ps aux | grep bash 
henry     7308  0.0  0.0   8988  5652 pts/3    S+   12:03   0:00 bash
henry     7482  0.0  0.0   8988  5500 pts/4    S+   12:03   0:00 bash
henry     7656  0.0  0.0   8988  5540 pts/5    S+   12:03   0:00 bash
henry     8776  0.0  0.0   6564  2176 pts/1    S+   12:08   0:00 grep --color=auto bash

$ ps aux | grep bash | excavate 1
7308
7482
7656
8826

The columns, regardless of your input order, will always be printed from low to high, i.e. from left to right in the table, and duplicates are ignored. excavate 1,2 is equivalent to excavate 2,1,1.

If a line has not enough columns, excavate ignores any field beyond the limit. For instance, running excavate 2,10 against the input bob alice eve gets you eve. Running it against bob alice gets you a blank line. The output always has the same number of lines as the input, even if some of them are empty.

Installation

At the moment, the program can be installed via cargo:

cargo install excavate

Build

excavate has only Rust dependencies, clap and nom. There's no external dependencies. Clone this repository, and run

cargo build