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Introduction

Em is a terminal tool that prints FILE(s), or standard input to standard output and highlights the expressions that are matched the PATTERN.

/_static/em-example.png

The expression will be highlighted iff the terminal is ANSI-compatible. This criterion is met by most popular terminal emulators on Linux, Unix and MacOS.

Installation

Em is a small script written in Python without any further dependencies but things that are shipped with Python 2.7, Python 3.2 or above. Quick installation:

$ [sudo] pip install em

Note

For some reason the Python 2.6 support has been added, but argparse is required and will be installed from PyPI.

Quickstart

Em is cool and easy to use. The most practical usecase for me:

$ tail -f /path/to/log | em "ERROR" | em "iphone:" -f green

The example above highlights all occurrences of «ERROR» in red and all occurrences of «iphone:» in green when watching the log.

But you can use em in the following way:

$ em "ERROR|CRITICAL" /path/to/log

which prints the log and highlights all occurrences of «ERROR» or «CRITICAL» in red.

Options

Here is a command line interface of Em:

usage: em [OPTION]... PATTERN [FILE]...

Em is a terminal tool that prints FILE(s), or standard input to standard
output and highlights the expressions that are matched the PATTERN.

positional arguments:
  PATTERN               a pattern to highlight
  FILE                  search for pattern in these file(s)

optional arguments:
  -f FORMAT, --format FORMAT
                        a color to highlight matched expressions
  -i, --ignore-case     ignore case distinctions
  -l, --line-mode       highlight entire line
  -v, --version         show program's version number and exit
  -h, --help            show this help message and exit

With no FILE, or when FILE is -, read standard input. The FORMAT option may be
one of: BOLD, UNDERLINE, [ON]GREY, [ON]RED, [ON]GREEN, [ON]YELLOW, [ON]BLUE,
[ON]MAGENTA, [ON]CYAN or [ON]WHITE. Default is RED.

The CLI is clear, but some option descriptions are below:

--format Highlight matched PATTERN with that color. (default: RED)
--ignore-case Case insensitive search for the PATTERN.
--line-mode Highlights the entire line if PATTERN was found in the line.

Contribute

Found a bug? Have a good idea for improving Em? Go to em's github page and create a new issue or fork. Also, if you like what I'm doing I would appreciate some support through gittip.