I'm trying to implement a simple terminal GUI using bash's interactive mode. I successfully invoked bash, get its stdout and print everything to a text view. I forward the user input from the text view to bash's stdin, to be able to run commands. It works great, except I don't get any error messages.
However, when I proceeded to print bash's stderr to my text view, I noticed something strange. In addition to now receiving error messages, bash seems to pass everything from stdin to stderr. Because of this, every character I type is printed twice (once normally because I enter it, and once because I print everything from stderr).
It also seems to print the prompt via stderr (bash-3.2$). Is this the expected behavior? Can this be suppressed?
I also tried to just capture use input (and not let the user type directly into the text view) and rely on bash to print the user input. This is almost working, except the order of the output via stdout and stderr is random:
If I type a command like echo test and hit enter, sometimes I get this:
(the second test is the output, I didn't type testtest)
bash-3.2$ echo testtest
bash-3.2$
Sometimes I get:
bash-3.2$ echo test
bash-3.2$ test
The order in which I receive the final \n, the output and the next bash-3.2$ is obviously mixed up.
There is no way to read stdout and stderr in the "correct" order, because there is no notion of order between different pipes. But you can ensure that both are sent to the same pipe (i.e. same file descriptor) instead of having each one go to a separate pipe. To do that, look on the options of whatever you use to start the bash subprocess; or maybe start a command line like bash -c 'bash 2>&1'.
Related
I workin' with Torch7 and Lua programming languages. I need a command that redirects the output of my console to a file, instead of printing it into my shell.
For example, in Linux, when you type:
$ ls > dir.txt
The system will print the output of the command "ls" to the file dir.txt, instead of printing it to the default output console.
I need a similar command for Lua. Does anyone know it?
[EDIT] An user suggests to me that this operation is called piping. So, the question should be: "How to make piping in Lua?"
[EDIT2] I would use this # command to do:
$ torch 'my_program' # printed_output.txt
Have a look here -> http://www.lua.org/pil/21.1.html
io.write seems to be what you are looking for.
Lua has no default function to create a file from the console output.
If your applications logs its output -which you're probably trying to do-, it will only be possible to do this by modifying the Lua C++ source code.
If your internal system has access to the output of the console, you could do something similar to this (and set it on a timer, so it runs every 25ms or so):
dumpoutput = function()
local file = io.write([path to file dump here], "w+")
for i, line in ipairs ([console output function]) do
file:write("\n"..line);
end
end
Note that the console output function has to store the output of the console in a table.
To clear the console at the end, just do os.execute( "cls" ).
I am trying a bit of experiments with airmon-ng script in Linux. Meanwhile i want to redirect output of a process "airodump-ng mon0" to a file. I can see the instantaneous output on the screen. The feature of this process is that it won't stop execution(actually it is a script to scan for AP and clients, it will keep on scanning) unless we use ctrl+c.
Whenever i try
airodump-ng mon0 > file.txt
i won't get the output in the file.
My primary assumption is that the shell will write it to the file only after completing the execution. But in the above case i stopped the execution(as the execution won't complete).
So to generalize i can't pipe the output of a running process to a file. How can i do that?
Or is there any alternative way to stop the execution of the process(for example after 5 seconds) and redirect the current output to a file?
A process may send output to standard output or standard error to get it to the terminal. Generally, the former is for information and the latter for errors, but in some cases, a process may mix them up.
I'm supposing that in your case, the standard error is being used. To get both of these to the output file, you can use:
airmon-ng mon0 > file.txt 2>&1
This says to send standard output to file.txt and to reroute 2 (which is the file id for standard error) into 1 (the file id for standard output) so that it also goes to the file.
I have a script which interacts with user (prints some questions to stderr and gets input from stdin) and then prints some data to stdin. I want to put the output of the script to a variable in vimscript. It probably should look like this:
let a = system("./script")
The supposed behavior is that script runs, interacts with user, and after all a is assigned with its output to stdout. But instead a is assigned both with outputs to stdout and stderr, so user seed no prompts.
Could you help me fixing it?
Interactive commands are best avoided from within Vim; especially with GVIM (on Windows), a new console window pops up; you may not have a fully functional terminal, ...
Better query any needed arguments in Vimscript itself (with input(); or pass them on from a custom Vim :command), and just use the external script non-interactively, feeding it everything it needs.
What gets captured by system() (as well as :!) is controlled by the 'shellredir' option. Its usual value, >%s 2>&1 captures stdout as well as stderr. Your script needs to choose one (e.g. stdout) for its output, and the other for user interaction, and the Vimscript wrapper that invokes it must (temporarily) change the option.
:let save_shellredir = &shellredir
:set shellredir=>
:let a = system('./script') " The script should interact via stderr.
:let &shellredir = save_shellredir
Call the script within the other as,
. ./script.sh
I think this is what you meant.
How to keep/promote with a multi line comment from the accurev command line?
For example if I try:
accurev stat -n -fl | xargs accurev keep -c "git log 1234..4311"
I simple get the error:
You can not use non-printable characters on the command line: # On
branch master\x0a... AccuRev was unable to understand your command.
I can of course strip out the new lines but then the comment is not really useful.
AccuRev commands that take a -c option for a comment must currently be enclosed in quotes and have no line breaks.
As for the output from git log 1234..4311 that could be captured as a manifest file and kept with the other files.
Dave
I'm not sure about doing it directly from the command-line without any extra step, and I'm hesitant to try anything on my client's AccuRev setup. That said, according to the entry on accurev keep from the CLI manual:
–c <comment>
Specify a comment for the transaction. The next command-line argument should be
a quoted string. Alternatively, the next argument can be in the form
#<comment-file>, which uses the contents of text-file <comment-file> as the
comment.
Default: enter a comment interactively, using the text editor named in
environment variable EDITOR (or a system-dependent default editor).
Reading this, I see two ways you can do what you want from the command line (meaning, not using the GUI).
1.) Pipe or cat your stat info into file, the use the #file syntax to get it into your commit
2.) Get your stat into into your clipboard, then don't give an argument to the keep command, let your editor open up, paste, save, and close.
There may be a way to get this all done via CLI without these middle-steps (perhaps you need to format the \x0a into \r\n or something?), but as I said, I'm unwilling to try it on my AccuRev setup as AccuRev gives me (and everyone else) enough trouble as it is.
HTH
I'm just switch to zsh and now adapting the alias in which was printing some text (in color) along with a command.
I have been trying to use the $fg array var, but there is a side effect, all the command is printed before being executed.
The same occur if i'm just testing a echo with a color code in the terminal:
echo $fg_bold[blue] "test"
]2;echo "test" test #the test is in the right color
Why the command print itself before to do what it's supposed to do ? (I precise this doesn't happen when just printing whithout any wariable command)
Have I to set a specific option to zsh, use echo with a special parameter to get ride of that?
Execute the command first (keep its output somewhere), and then issue echo. The easiest way I can think of doing that would be:
echo $fg[red] `ls`
Edit: Ok, so your trouble is some trash before the actual output of echo. You have some funny configuration that is causing you trouble.
What to do (other than inspecting your configuration):
start a shell with zsh -f (it will skip any configuration), and then re-try the echo command: autoload colors; colors; echo $fg_bold[red] foo (this should show you that the problem is in your configuration).
Most likely your configuration defines a precmd function that gets executed before every command (which is failing in some way). Try which precmd. If that is not defined, try echo $precmd_functions (precmd_functions is an array of functions that get executed before every command). Knowing which is the code being executed would help you search for it in your configuration (which I assume you just took from someone else).
If I had to guess, I'd say you are using oh-my-zsh without knowing exactly what you turned on (which is an endless source of troubles like this).
I don't replicate your issue, which I think indicates that it's either an option (that I've set), or it's a zsh version issue:
$ echo $fg_bold[red] test
test
Because I can't replicate it, I'm sure there's an option to stop it happening for you. I do not know what that option is (I'm using heavily modified oh-my-zsh, and still haven't finished learning what all the zsh options do or are).
My suggestions:
You could try using print:
$ print $fg_bold[red] test
test
The print builtin has many more options than echo (see man zshbuiltins).
You should also:
Check what version zsh you're using.
Check what options (setopt) are enabled.
Check your ~/.zshrc (and other loaded files) to see what, if any, options and functions are being run.
This question may suggest checking what TERM you're using, but reading your question it sounds like you're only seeing this behaviour (echoing of the command after entry) when you're using aliases...?