cosmos72
feature request: shell commands
Would be great to run commands prefixed with ! in a shell like in ipython (and others?), eg
gomacro> !ls -la
drwxr-xr-x 6 peter staff 204 12 Jul 22:49 .
drwxr-xr-x 3 peter staff 102 12 Apr 2014 ..
drwxr-xr-x 140 peter staff 4760 19 Mar 2016 5072f70927f95a13e54e775676c51ee144a14dd7
drwxr-xr-x 264 peter staff 8976 13 Aug 2017 5a774f194ac60210f83ba3cfa6c7a769f5600dee
More examples https://jakevdp.github.io/PythonDataScienceHandbook/01.05-ipython-and-shell-commands.html#Shell-Commands-in-IPython
It would be useful - I am just wondering whether it's slightly out of scope or not...
If implemented, we will have to choose a different special char for shell commands:
! is negation in go, and can already appear at line start - for example !foo() && !bar().
Maybe $ ?
: is used as a prefix to indicate interpreter commands, so how about :!ls -la (! is used for shell in many programs)?
As for being out of scope, I think it's a pretty common REPL feature.
Both :!ls -la and \!ls -la are feasible, but I think we can do better:
Special commands take a whole line, and can only used at top level, so exchanging data between a special command and Go must be implemented manually by the special command.
If instead I implement an expression that invokes the shell and returns its output (and error),
it can be used anywhere - inside functions, as for condition, etc.
What do you think about something like:
// plain shell syntax, prefix is $
$ls -al
to run a shell command and collect its output as []string, surround it with $()
for i, name := range $(ls -al) {
println(name)
}
to pass Go expressions (variables, function/method calls...) to shell command, surround them with {} like ipython does:
dir := "/usr/bin"
for i, name := range $(ls -al {dir}) {
println(name)
}
standard error would be available as second return value:
out, err := $(some_command)
Using ,? If the first char of an input is , the line is treated as shell.
I believe , cannot be a valid char to start an expression. Also , (and .) is right below finger tip and there is no need for shift key. Dot (.) would be nice but it can be the first char of a valid expression (.6 as floating point).
