acoc - Arbitrary Command Output Colourer

Ever wondered why the output of your favourite UNIX/Linux commands is still displayed in black-and-white after all these years?

traceroute (green = fast, red = slow)

w

top (with root's processes shown in red)

Building an RPM with rpmbuild

Dependencies

The configuration files used by the program are /usr/local/etc/acoc.conf, /etc/acoc.conf and ~/acoc.conf. One or more of these must exist. A sample /etc/acoc.conf is supplied with some example matching rules.

Blank lines and those that begin with a # are ignored.

A program configuration stanza is introduced as follows:

[program_spec]

The square brackets are mandatory literal characters. Alternatively, the @ symbol may be used, to allow [ and ] to retain their usual semantics in program specs comprising a regular expression:

@program_spec@

program_spec is defined as one or more instances of the following component, separated by a comma:

invocation[/flags]

where invocation consists of the program's name (not including its directory path component) plus any initial arguments.

Alternatively, invocation may be a regular expression, which can be used to match multiple programs and/or command-line arguments in arbitrary order. Regular expressions are automatically anchored to the beginning of the command line.

flags, if present, is separated from 'invocation' by a slash and consists of one or more of the following characters:

a

continue to attempt to find matching patterns after the first match has been found. By default, acoc will stop processing a line and display it after the first match has been found.

e

redirect the target program's stderr to stdout, allowing it, too, to be matched by rules

p

allocate a pseudo-terminal in which to run the target program

Some programs, such as ls(1), behave differently when their stdout is not connected to a tty. Use of this option will fool the target program into believing it is outputting to a tty, rather than a pipe to acoc.

Use of this flag requires Masahiro Tomita's Ruby/TPty library to be installed. Otherwise, the flag is silently ignored.

Note that the pseudo-terminal communication enabled by this flag is one-way only, from the target program to acoc. It is thus not possible to use acoc in combination with interactive programs, such as the interactive Ruby interpreter (irb).

t

apply colour formatting even if stdout is not a tty. By default, formatting is not applied if the output stream is not attached to a terminal.

Here's an example of a line that introduces a configuration stanza:

[rpm/ae,rpmbuild/ae]

which says to apply the following rules to the rpm and rpmbuild commands, attempt to apply all matching rules, and also apply those rules to the programs' stderr stream.

Another example:

[ls/p]

This says to allocate a pseudo-terminal to ls(1), fooling it into believing that its output is being sent to a regular terminal instead of a pipe to acoc.

With this flag, the effect will be this:

$ ls
file1  file2  file3  file4  file5  file6

Without it, ls will detect that its stdout is connected to a pipe and behave accordingly:

$ ls
file1
file2
file3
file4
file5
file6

A third example:

[diff/t,rcsdiff/t,cvs diff/t,p4 diff/t]

This says that the rules that follow should be applied to all invocations of diff(1) and rcsdiff(1), as well as those invocations of cvs(1) and p4 that are followed by the argument diff.

Additionally, colouring should be applied even when stdout is not connected to a tty, so that the colours still show up when the output is displayed in a pager such as more(1) or less(1).

Yet another example:

/ps -.*(e.*f|f.*e)/

In this example, the ps(1) command will be matched, as long as the e and f options are both passed in either order.

An alternative way to write the above spec is:

@ps -.*[ef].*[ef]@

There are two things to note in this alternative:

1. @ has been used to delimit the spec, because [ and ] are required for the character lists in the regular expression.
2. While this form is less specific (in that it allows matches against duplicated command line options), it makes for considerably shorter specs if one wishes to test for the inclusion of a set of more than 2 or 3 command line flags. In the original form, one must manually list all of the possible permutations, which is equal to x! (factorial). For 3 command line flags, this is 6 permutations; for 4, it is 24, etc.

Here's one more example:

[tcpdump/r]

If this were placed in ~/.acoc.conf, it would remove any matching rules that had been installed for the diff command by either /etc/acoc.conf or /usr/local/etc/acoc.conf.

After defining the program name and operational flags, matching rules can be defined. These take the following form:

/regex/[flags] colour_spec

where regex is a Ruby-compatible regular expression. The delimiting / characters can be any character, as long as that character is not present in the regular expression itself. flags, if present, consists of one or more characters from the following list:

g

find every match on the line, not just the first. When using this flag, 'regex' should not include parentheses.

• black
• blink
• blue
• bold
• clear
• concealed
• cyan
• dark
• green
• italic
• magenta
• negative
• on_black
• on_blue
• on_cyan
• on_green
• on_magenta
• on_red
• on_white
• on_yellow
• rapid_blink
• red
• reset
• strikethrough
• underline
• underscore
• white
• yellow

Examples of a colour_group are white+bold, black+on_white, etc. A complete colour_spec might look like this:

red+bold,white,yellow+bold,black+on_green

Except when using the g flag, each component of the regex that you wish to colour should be placed in parentheses. Text outside parentheses will be used for matching, but will not be coloured.

For example, examine the following:

/^(\d+)foo\s*(\w+)/

This will match a line that starts with more or one digits, followed by the string foo and any amount of white space, followed by one or more word characters. However, only the initial group of digits and the group of word characters will be coloured. The string foo and the white space that follows it will be used for matching, but will not be coloured.

Separated from the regex by white space is the colour_spec. Usually, you will include in this as many colours (separated by commas) as you have parenthesised expressions in the regex. However, it's also permissible to have fewer. If, for example, you have three parenthesised expressions in the regex, but only two colours listed in the colour_spec, then the second colour will be used for colouring both the second and third matches.

If you have more colours listed in the colour_spec than there are parenthesised expressions in the regex, the surplus colours are ignored.