Propellor.Property.Cmd

This module lets you construct Properties by running commands and scripts. To get from an UncheckedProperty to a Property, it's up to the user to check if the command made a change to the system.

The best approach is to check a property, so that the command is only run when it needs to be. With this method, you avoid running the cmdProperty unnecessarily.

check (not <$> userExists "bob")
	(cmdProperty "useradd" ["bob"])

Sometimes it's just as expensive to check a property as it would be to run the command that ensures the property. So you can let the command run every time, and use changesFile or checkResult to determine if anything changed:

cmdProperty "chmod" ["600", "/etc/secret"]
	`changesFile` "/etc/secret"

Or you can punt and assume a change was made, but then propellor will always say it make a change, and onChange will always fire.

cmdProperty "service" ["foo", "reload"]
	`assume` MadeChange

Constricting properties running commands and scripts

cmdProperty :: String -> [String] -> UncheckedProperty UnixLike

A property that can be satisfied by running a command.

The command must exit 0 on success.

cmdProperty' :: String -> [String] -> (CreateProcess -> CreateProcess) -> UncheckedProperty UnixLike

cmdPropertyEnv :: String -> [String] -> [(String, String)] -> UncheckedProperty UnixLike

A property that can be satisfied by running a command, with added environment variables in addition to the standard environment.

type Script = [String]

A series of shell commands. (Without a leading hashbang.)

scriptProperty :: Script -> UncheckedProperty UnixLike

A property that can be satisfied by running a script.

userScriptProperty :: User -> Script -> UncheckedProperty UnixLike

A property that can satisfied by running a script as user (cd'd to their home directory).

cmdResult :: Bool -> Result

Lower-level interface for running commands

data CommandParam

Parameters that can be passed to a shell command.

Constructors

Param String

A parameter

File FilePath

The name of a file

Instances

Show CommandParam

Defined in Utility.SafeCommand

Methods

showsPrec :: Int -> CommandParam -> ShowS

show :: CommandParam -> String

showList :: [CommandParam] -> ShowS

Eq CommandParam

Defined in Utility.SafeCommand

Methods

(==) :: CommandParam -> CommandParam -> Bool

(/=) :: CommandParam -> CommandParam -> Bool

Ord CommandParam

Defined in Utility.SafeCommand

Methods

compare :: CommandParam -> CommandParam -> Ordering

(<) :: CommandParam -> CommandParam -> Bool

(<=) :: CommandParam -> CommandParam -> Bool

(>) :: CommandParam -> CommandParam -> Bool

(>=) :: CommandParam -> CommandParam -> Bool

max :: CommandParam -> CommandParam -> CommandParam

min :: CommandParam -> CommandParam -> CommandParam

boolSystem :: FilePath -> [CommandParam] -> IO Bool

Run a system command, and returns True or False if it succeeded or failed.

This and other command running functions in this module log the commands run at debug level, using System.Log.Logger.

boolSystemEnv :: FilePath -> [CommandParam] -> Maybe [(String, String)] -> IO Bool

safeSystem :: FilePath -> [CommandParam] -> IO ExitCode

Runs a system command, returning the exit status.

safeSystemEnv :: FilePath -> [CommandParam] -> Maybe [(String, String)] -> IO ExitCode

shellEscape :: String -> String

Escapes a filename or other parameter to be safely able to be exposed to the shell.

This method works for POSIX shells, as well as other shells like csh.

createProcess :: CreateProcess -> IO (Maybe Handle, Maybe Handle, Maybe Handle, ProcessHandle)

Wrapper around createProcess that does debug logging.

waitForProcess :: ProcessHandle -> IO ExitCode

Wrapper around waitForProcess that does debug logging.