Scripting on Linux

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How to determine what operating system you're running on:

from Python: read the sys.platform variable;
from PHP: call the php_uname function;
from Tcl: look it up in the global tcl_platform array;
from Perl: use the $^O predefined variable as per the perlvar man page.

How to figure out where to save configuration files for the current operating system:

def config_home() -> str:
	"""Get storage dir for user config files as per the XDG spec."""
	if os.getenv("XDG_CONFIG_HOME"):
		return str(os.getenv("XDG_CONFIG_HOME"))
	elif sys.platform.startswith("haiku"):
		result = subprocess.run(
			["finddir", "B_USER_SETTINGS_DIRECTORY"],
			capture_output=True)
		return result.stdout.decode()
	else:
		return os.path.join(str(os.getenv("HOME")), ".config")

Text user interfaces

How to use the dialog utility from Tcl:

package require Tcl 8.5
set temp [file tempfile]
exec dialog --inputbox "What's your name?" 0 0 <@ stdin >@ stdout 2>@ $temp
seek $temp 0
exec dialog --msgbox "Hello, [read $temp]" 0 0 <@ stdin >@ stdout
seek $temp 0
chan truncate $temp
exec dialog --inputbox "What's up?" 0 0 <@ stdin >@ stdout 2>@ $temp
seek $temp 0
puts "[read $temp] is cool!"

How to use dialog from Perl:

use warnings;
use strict;

use IPC::Open3 'open3';
use Symbol 'gensym';

system "dialog", "--msgbox", "Hello, world!", "0", "0";

my $pid = open3('<&STDIN', '>&STDOUT', my $dlgout = gensym,
	"dialog", "--inputbox", "What's your name?", "0", "0");

waitpid($pid, 0);

print "Nice to meet you, ", <$dlgout>, "!\n";
close $dlgout;

Note: Perl also has the UI::Dialog library (packaged in Debian as libui-dialog-perl). Other solutions:

For Python, there's pythondialog (packaged in Debian as python3-dialog) but it's easy enough to roll your own.
For C, dialog also comes with a native library.

Scripting on Linux

Text user interfaces

Language links

Shell script

Bash

Zsh

Awk