The command line

Babbage has a second face. bbg is the same program as the window, run as a calculator: give it an expression or a sheet and it prints the answers, then exits. The answers are the window's, because both use the same settings, the same global variables and the same formats. Nothing opens on your screen.

The one-line installer puts bbg next to babbage in ~/.local/bin; see Getting started. babbage calc does the same job as bbg for anyone who would rather not have the extra command.

Answer an expression

Put the expression after bbg. The words are joined into one line, and only the answer is printed.

$ bbg 20% of 85
17

$ bbg 150 lb in kg
68.0388555 kg

A line that has no answer, such as a variable being set, prints nothing and exits with status 0.

Start the expression with - followed by a number and it is still an expression: bbg -5 + 3 prints -2. If the expression starts with a dash and a letter, put -- before it.

Answer a sheet file

Give bbg the path of a sheet, and it answers every line. Each line's text is printed, then its answer, in two columns that line up. A sheet is the same plain text file the window saves, so a file you wrote in an editor works too. Here is groceries.bbg:

Groceries
milk $3.20 × 2
bread $4.50
eggs $5.10

$ bbg -t groceries.bbg
Groceries
milk $3.20 × 2  $6.40
bread $4.50     $4.50
eggs $5.10      $5.10
Total           $16.00

The -t option adds the total, which is the same sum the window's Total chip shows. A file's per-line choices (decimal places and the rest, set from a line's answer menu in the window) are used as they are.

Answer a saved sheet

-s takes the name of a sheet in the sheet folder, the same folder the window uses (see Sheets and files). The name is the sheet's file name without .bbg.

$ bbg -s Groceries
Groceries
milk $3.20 × 2  $6.40
bread $4.50     $4.50
eggs $5.10      $5.10

Read standard input

With no arguments, bbg reads a sheet from standard input when the input is not a terminal. A single - does the same, and so does -f -. This is how it works in a pipeline:

$ echo "3 * \$4.50" | bbg
3 * $4.50  $13.50

Choose what is printed

Decimal places and repeating decimals print the same way the window prints them. When a rounded or approximate answer is shown, it has the window's ≈ mark:

$ bbg -p 2 1/3
≈ 0.33

$ bbg -r 1/3
0.(3)

With --json, exact is false for an answer marked ≈:

$ bbg --json "12 + 8"
{"text":"12 + 8","answer":"20","exact":true,"error":null}

With -a, only the answers are printed, so a script can read them line by line:

$ bbg -a groceries.bbg
$6.40
$4.50
$5.10

Errors and exit status

A line that has an error prints its message on standard error when only answers are printed, and in its answer column in a sheet. Either way the exit status is 1.

$ bbg "1 +"
unexpected end of expression

Tab completion

Press Tab after bbg - for the options, after -p for the decimal places, and after -s for the names of your saved sheets. The one-line installer sets this up for bash, and for fish when you use fish, with one file of its own for each (~/.local/share/bash-completion/completions/bbg and ~/.config/fish/completions/bbg.fish). It never replaces a file of that name that it did not write, and --uninstall removes only its own.

To set it up yourself, or for zsh, ask bbg for the script:

bbg --list-sheets prints the saved sheet names, one per line, for your own scripts. It only reads the sheet folder: it creates nothing and cleans nothing up, so it is safe to run at any time.

Where it gets its settings

bbg reads the same settings file as the window (~/.config/babbage/settings, or the file named by BABBAGE_CONFIG_FILE), so your time zone, number format, decimal places and global variables apply. The variables you set in Settings work in an expression too: bbg rent * 12 uses the rent you defined. See Settings for each setting.