:: String -> IO ()
Write a string to the standard output device
putStr is implemented as
hPutStr stdout.
This operation may fail with the same errors, and has the same issues
with concurrency, as
hPutStr!
Examples
Note that the following do not put a newline.
>>> putStr "Hello, World!"
Hello, World!
>>> putStr "\0052\0042\0050"
4*2
The same as
putStr, but adds a newline character.
This operation may fail with the same errors, and has the same issues
with concurrency, as
hPutStr!
The
traceIO function outputs the trace message from the IO
monad. This sequences the output with respect to other IO actions.
The
traceEventIO function emits a message to the eventlog, if
eventlog tracing is available and user event tracing is enabled at
runtime.
Compared to
traceEvent,
traceEventIO sequences the event
with respect to other IO actions.
The
traceMarkerIO function emits a marker to the eventlog, if
eventlog tracing is available and user event tracing is enabled at
runtime.
Compared to
traceMarker,
traceMarkerIO sequences the
event with respect to other IO actions.
unsetEnv name removes the specified environment variable from
the environment of the current process.
Throws
IOException if
name is the empty string or
contains an equals sign.
Beware that this function must not be executed concurrently with
getEnv,
lookupEnv,
getEnvironment and such. One
thread reading environment variables at the same time with another one
modifying them can result in a segfault, see
Setenv is not Thread
Safe for discussion.
Like
unsetEnv, but allows for the removal of blank environment
variables. May throw an exception if the underlying platform doesn't
support unsetting of environment variables.
Beware that this function must not be executed concurrently with
getEnv,
lookupEnv,
getEnvironment and such. One
thread reading environment variables at the same time with another one
modifying them can result in a segfault, see
Setenv is not Thread
Safe for discussion.
Creates a new process to run the specified shell command. If the
command returns a non-zero exit code, an exception is raised.
If an asynchronous exception is thrown to the thread executing
callCommand, the forked process will be terminated and
callCommand will wait (block) until the process has been
terminated.
putEnv function takes an argument of the form
name=value and is equivalent to
setEnv(key,value,True{-overwrite-}).
The
unsetEnv function deletes all instances of the variable
name from the environment.
Delete the semaphore with the given name.
Delete the shared memory object with the given name.
The same as
putStr, but adds a newline character.
Write a string to the standard output device (same as
hPutStr
stdout).
Create a directory with permissions so that only the current user can
view it. On Windows this function is equivalent to
createDirectory.
Send a comment which will be displayed on the calling console, mainly
useful for debugging.
Set the terminal window title and icon name (that is, the text for the
window in the Start bar, or similar).