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Oil Builtins

• use
• push, repr
• wait, fork

Enhanced with Block

• cd

(not done)

• wait
• env (not done)
• shopt

Shell-Like Builtins

Builtins Accept Long Options
Changed: echo
New: use, push, repr

Builtins Can Take Ruby-Like Blocks (partially done)

cd, env, and shopt Have Their Own Stack
wait and fork builtins Replace () and & Syntax
each { } Runs Processes in Parallel and Replaces xargs

cd

It now takes a block:

cd ~/src {
  echo $PWD
  ls -l
}

# current directory restored here

echo $PWD
ls -l

(This subsumes the functinoality of bash builtins pushd and popd.)

When a block is passed:

• cd doesn't set The OLDPWD variable (which is used to implement the cd - shortcut.)
• The directory stack for pushd and popd isn't cleared, as it is with a normal cd command.

push

Append one or more strings to an array.

var array = @(1 '2 two')
push :array three four
echo @array  # prints 4 lines

Builtin Flag Syntax

Oil's builtins accept long flags like --verbose and short flags like -v.

They behave like the popular GNU utilities on Linux distros, except that -long (single hyphen) means the same thing as --long. It's not a shortcut for -l -o -n -g or -l=ong. (This rule is consistent with the Go flags package.)

In addition, all of these are equivalent:

• -sep x
• -sep=x
• --sep x
• --sep=x

The first is preferred because it's the simplest and shortest.

(Trivia: Oil's flag syntax avoids the issue where set -oo errexit nounset is a confusing equivalent to set -o errexit -o nounset.)

I/O Builtins

Oil uses write and getline along with the CSTR format. echo looks more familiar and is OK in many cases, but isn't strictly necessary.

Shell:

• uses echo and read
• echo isn't good because echo $x is a bug
• read isn't good because -r isn't the default. And the \ format doesn't occupy one line.

Oil:

• write -- @items
  • --sep $'\t', --end $'\n' (do we need shorthand?)
  • -n is a shortcut --end ''
  • write --cstr -- @items
• getline
  • --cstr

echo

• -sep: Characters to separate each argument. (Default: newline)
• -end: Characters to terminate the whole invocation. (Default: newline)
• -n: A synonym for -end ''.

More

Future work, not implemented

• fork, wait
• log, die
• write