Bash Utility

General

opal:bash_intro

Write the file header bash comment to the top of a bash file.

This is best used in a script for creating new files. The header writes three values to the file header - the Generator, Date-Created, and Author. The Generator is the application creating the file. The Date-Created reports the time the date and time the file was created, in the opal-datetime format. The author is the username who ran the functions, which created the file.

@param String $filename

@output void

$ opal:bash_intro ~/.bashrc

The output is written to the filename passed. Here’s an example of the output.

#
# Generator: Opal <https://github.com/andrewwoods/opal>
# Date-Created: 2026 Apr 19 Sun 11:49
# Author: your_username
#

opal:vim_intro

Write the file header Vim comment to the top of a Vim file.

This is best used in a script for creating new files. The header writes three values to the file header - the Generator, Date-Created, and Author. The Generator is the application creating the file. The Date-Created reports the time the date and time the file was created, in the opal-datetime format. The author is the username who ran the functions, which created the file.

@param String $filename

@output void

$ opal:bash_intro ~/.vimrc

The output is written to the filename passed. Here’s an example of the output.

"
" Generator: Opal <https://github.com/andrewwoods/opal>
" Date-Created: 2026 Apr 19 Sun 11:49
" Author: your_username
"

opal:bash_heading_box

Write the section heading box to a file

This utility for creating a section header is best used in a script for creating new files.

@param String $heading

@param String $filename

@output void

$ opal:bash_heading_box 'My Heading' ~/.bashrc

opal:preamble

Display the system preamble

Show the user some information to greet them when opening a new terminal.

@output String

$ opal:preamble

opal:up

Navigate up the file system a number of directories. Default 1.

Often you want to travel up a numnber of directory levels.

~/src/public/opal-documentation-rtd $ opal:up 2

~/src/ $

opal:type_file

Dynamically display a text file.

An animated version of echo. Gives the sense of typing the file text to STDOUT.

@uses bin/typer

$ opal:type_file filename.txt

opal:type_line

Dynamically display a line of text.

An animated version of echo. Gives the sense of typing the text to STDOUT.

@uses bin/typer

$ opal:type_line "Hello World"

opal:spacer

Create a number of blank lines. By default, creates a single blank line.

Sometime you need to create vertical white space.

@param Integer $quantity

The number of blank lines to create. Default = 1.

@output string

$ opal:spacer 4

Date-related

opal:filedate_to_day

Sometimes, you need to know the day of the week for a given date.

Convert the output of opal:today filename-date and opal:today filename-timestamp to a weekday. This is use for when you want to create a report title based on the the use of dates.

@param String $date

The date must be formatted in YYYY-MM-DD for YYYY-MM-DD-hh-mm-ss format

@output String

$ opal:filedate_to_date 2026-03-25
Wed

opal:monday_date

Monday is the first day of the current week. Get Monday’s date.

@output String

$ opal:monday_date # The current date is 2026 Mar 25 Wed 17:00
2026 Mar 23 Mon

opal:sunday_date

Sunday is the last day of the current week. Get Sunday’s date.

@param String $date_format

@output String

@uses opal:get_date_format

$ opal:sunday_date # The current datetime is 2026 Mar 25 Wed 17:00
2026 Mar 29 Sun

opal:cal3

Display a current 3-month span. The previous month, current month, and the next month. The output is displayed vertically. The command cal -3 can be used to display the calendars positioned horizontaly.

    February 2026
Su Mo Tu We Th Fr Sa
 1  2  3  4  5  6  7
 8  9 10 11 12 13 14
15 16 17 18 19 20 21
22 23 24 25 26 27 28


     March 2026
Su Mo Tu We Th Fr Sa
 1  2  3  4  5  6  7
 8  9 10 11 12 13 14
15 16 17 18 19 20 21
22 23 24 25 26 27 28
29 30 31

     April 2026
Su Mo Tu We Th Fr Sa
          1  2  3  4
 5  6  7  8  9 10 11
12 13 14 15 16 17 18
19 20 21 22 23 24 25
26 27 28 29 30

opal:ncal3

Display a current 3-month span. The previous month, current month, and the next month. The output is displayed vertically. The command ncal -3 can be used to display the calendars positioned horizontaly.

$ opal:ncal3

    February 2026
Mo     2  9 16 23
Tu     3 10 17 24
We     4 11 18 25
Th     5 12 19 26
Fr     6 13 20 27
Sa     7 14 21 28
Su  1  8 15 22

    March 2026
Mo     2  9 16 23 30
Tu     3 10 17 24 31
We     4 11 18 25
Th     5 12 19 26
Fr     6 13 20 27
Sa     7 14 21 28
Su  1  8 15 22 29

    April 2026
Mo     6 13 20 27
Tu     7 14 21 28
We  1  8 15 22 29
Th  2  9 16 23 30
Fr  3 10 17 24
Sa  4 11 18 25
Su  5 12 19 26

opal:greeting

Greet the user based on the time of day.

@output String $greeting

@uses opal:preamble

$ opal:greeting
Good afternoon

opal:mach

Disable information about your system.

$ opal:mach

Machine information:
Darwin Aerilon.local 22.6.0 Darwin Kernel Version 22.6.0: Tue Jul 15 08:22:28 PDT 2025; root:xnu-8796.141.3.713.2~2/RELEASE_X86_64 x86_64

Users logged on:
awoods   console  -  29Mar26 20days -
awoods   s000     -  29Mar26 1day  -bash         ˇø    /bin/bash
awoods   s001     -  29Mar26 1day  -bash         ˇø    /bin/bash
awoods   s002     -  07Apr26     - tmux attach -t WRITE
awoods   s025     -  Fri14   2days -bash         ˇø    /bin/bash

Current date :
Sun Apr 19 15:09:42 EDT 2026

Machine status :
15:09  up 20 days, 23:49, 5 users, load averages: 1.49 1.61 1.65

Filesystem status :
Filesystem       Size   Used  Avail Capacity iused       ifree %iused  Mounted on
/dev/disk1s4s1  1.8Ti   18Gi  1.4Ti     2%  356882  4290768130    0%   /
devfs           201Ki  201Ki    0Bi   100%     696           0  100%   /dev
/dev/disk1s2    1.8Ti  4.0Gi  1.4Ti     1%    1392 14840563680    0%   /System/Volumes/Preboot
/dev/disk1s6    1.8Ti  4.0Gi  1.4Ti     1%       4 14840563680    0%   /System/Volumes/VM
/dev/disk1s5    1.8Ti   74Mi  1.4Ti     1%     538 14840563680    0%   /System/Volumes/Update
/dev/disk1s1    1.8Ti  421Gi  1.4Ti    23% 3743229 14840563680    0%   /System/Volumes/Data
map auto_home     0Bi    0Bi    0Bi   100%       0           0  100%   /System/Volumes/Data/home
/dev/disk1s4    1.8Ti   18Gi  1.4Ti     2%  455010  4290100123    0%   /System/Volumes/Update/mnt1

User Experience

opal:country

Lookup a country name for a given 2-letter or 3-letter country code.

$ opal:country ca
Looking up CA ...
CANADA

opal:define

Lookup the definitions for an English word using dict.org

$ opal:define computer

opal:say_done

Use Mac’s say command to convert simple message to sound.

By default, the message will say “It is Done!”. This is useful when completing a long running command, and you don’t want to stare at your terminal.

$ opal:say_done

$ opal:say_done "The script has completed"

opal:show_dotfiles

Allow you to turn on and off the display of hidden files in Apples Finder.

Note: This doesn’t affect the ls command.

@param String $choice

Can be on, off, true, or false

@output void

$ opal:show_dotfiles yes

$ opal:show_dotfiles no