Many terminal programs will behave differently depending on the STDOUT destination, either terminal or pipe or file. Usually they will remove colors. There are usually command line options for some of them to keep colors or formatting or anything else that is intended only for direct terminal output. But those options are not always present and it takes time to find them thus I need a generic way to trick the program so that it thinks that STDOUT is terminal, not a pipe. How to achieve this?
There are several tools for this, they basically create a pty for your command.
The best known is probably expect: http://expect.sf.net
Alternatively, empty: http://empty.sf.net
There are several examples in that page, have a look.
For simple cases, script -c 'mycommand' may be a viable alternative.
And tmux, which is powerful and pretty easy to script.
Related
Using the Turtle shell scripting library I am trying to launch a program, i.e:
shell "vim" empty
The problem is that this yields the warning Warning: Input is not from a terminal and causes Vim to lag for a few seconds before finally launching.
Questions:
Is shell the best Turtle function to launch an external program from haskell?
If so, is there any way to get around errors like the above?
You want to use functions from the process library, specifically createProcess or runProcess.
Relevant turtle thread on the issue here.
Example usage.
You could try manually setting up I/O to the vty. E.g. in bash: vim < $TTY > $TTY. I guess turtle is doing that with its own file descriptors under the hood, based on the warning, so you should be able to manually set up those redirects (or just use the command I gave via shell). You just need to make sure you've got a TTY environment var around.
I'm trying to make a bash script that behaves differently based on the terminal program that someone is using (Putty, mobaxterm, etc). Is there any way to retrieve this kind of information from a bash script?
I was searching around online but I was not able to find anything (or I'm just wording it incorrectly, which could be a distinct possibility).
thank you
You need to understand that these are terminal emulators. There is a simple, crude identification function for (most?) modern line terminals (now that's an oxymoron!) but it will return something like vt102 or xterm i.e. whatever the emulator is emulating; not the identity of the program performing this emulation. Incidentally, this is usually used when the session is initiated, and reflected in the value of the $TERM environment variable.
The common way to do this is the environment variable TERM. Try
echo $TERM
That should output the terminal emulator's type, indicating its capabilities. Often, though not always, the value of TERM will be the name of the terminal emulator. For example, xterm may set TERM to xterm, or to xterm-color, depending on configuration.
Note that the user can change this variable, so it may contain something completely different.
That said, if you want to do fancy things with the terminal from a script, you don't need to build support for different terminals by hand. There are various libraries that offer all the usual functions (clear terminal, resize window, change font etc.). The most popular one is terminfo; there are various packages that build on terminfo.
I've created a couple of very simple bash scripts for a home-made games arcade (input configuration, updating stuff etc). I've got a launcher, so it's not a problem to direct the user to run the wanted shell script, but while running a bash script functionality-wise gives me everything I need, the default low-res text-on-black look scares the end user.
What is the simplest way to "prettify" fullscreen shell scripts? Something that'll run the script in 1080p, use bigger bubbly antialiased fonts, add a fancy animated background etc., but still pretty much lets me stick to write good-old shell scripts?
I guess another way to ask is: Does a prettier, more modern GUI-looking alternative to whiptail exist?
I am running from the terminal, so the GUI library it would have to be as fully self-contained as possible.
The ability of a shell script to display a quit within the terminal window itself is limited entirely to the graphical capabilities of the terminal (and to what termcap/terminfo has support for).
Most terminals max out at 256 colors (though supposedly konsole has support for arbitrary RGB colors somehow).
Control over font sizing/etc. from the shell is limited to the escape sequences that the terminal is willing to respond to (and I don't know if those are at all standard or discoverable at runtime).
The best option for this might be to have your script re-exec itself in a new terminal window to which it passes appropriate arguments to control font selection, window geometry, color selection, etc.
That being said even reliably doing that isn't necessarily the easiest thing in the world (I'm not sure how portable the command line options are between different terminal emulators or how many more advanced features they expose).
You could use python with the library Gooey that makes easy to turn CLI applications to GUI:
It can be customized and it takes only one line for the magic to happen:
from gooey import Gooey
#Gooey <--- all it takes! :)
def main():
# rest of code
I can scroll trough bash output using shift+pgup/pgdown.
But lets say, some command outputted lot of text, I have to pageup few times to go to beginning of output of this command.
Can I just simply do this by some shortcut? Something that simply allows me to scroll between previous commands (not history!), seeing their output.
You could try piping the output into less:
someCommand | less
less will allow you to search and scroll through the output text pretty easily.
once in less you can just type % to jump back to the top of the page. Essentially that means jump to 0% of the page. There are also a bunch of extra commands on the page I linked to above.
Another option is to use screen and use backward search (beware: read the Overview first, especially the part about the C-a prefix) to e.g. search for some specific characters in your prompt (like your username).
The scroll back history in Unix shells is a shell specific functionality, meaning that it is up to the specific shell (xterm, rxvt, text console, etc) to handle it. The functionality you request would require the shell to identify the individual program runs, to know where to scroll to. Scanning text is not technically hard per se, but as prompts and command display can differ due to user settings it can be hard to make it work generally good. Some communication between the shell and the terminal could make it better.
There sure are some nice fancy terminal programs doing things like this, to for example show syntax help when writing commands, but for your case I agree with previous answer, that piping commands to less is a good way to isolate the output. It might be a bit cumbersome first, as it requires you to think about it first, and not just go back in history, but if you learn the shell better and learn to use the command history it will probably work fine. I recommend you to, if you haven't already. What I mean is ctrl-r etc. More described for example here:
http://www.catonmat.net/blog/the-definitive-guide-to-bash-command-line-history/
How can you set a string to be used instead of standard input? For example, when running the latex command in Unix it will always find some trivial errors, to skip through all errors you have to enter "r" into the command line (I now know that with latex specifically you can use -interactionmode nonstopmode, but is there a more general solution to do this?)
Is there anyway to specify that this should be done automatically? I tried redirecting standard input to read from a file containing "r\n", but this didn't work.
How can I achieve this?
Not all applications that need input can be satisfied with their stdin redirected.
This is because the app can call the isatty C function (if written in C, or some equivalent call for other languages) to determine if the input come from a tty or not.
In such situation, there is a valuable tool to use, and this is expect.
latex --interaction=MODE
where MODE is one of:
errorstopmode: stop at every error and ask for input
scrollmode: scroll over non-fatal errors, but stop at fatal errors (such as "file not found")
nonstopmode: scroll over non-fatal errors, abort at fatal errors
batchmode: like nonstopmode, but don't show messaes at the terminal
For interactive use, errorstopmode (the default) is fine, for non-interactive use, nonstopmode and batchmode are better.
But beware, there are no trivial errors: all errors must be fixed, and all warnings should be fixed if possible.
Redirecting stdin works without problems here:
/tmp $ tex '\undefined\end' <<< r
This is TeX, Version 3.1415926 (TeX Live 2010)
! Undefined control sequence.
<*> \undefined
\end
? OK, entering \nonstopmode...
(see the transcript file for additional information)
No pages of output.
Transcript written on texput.log.
You've got two plausible answers detailing the way to handle Latex specifically. One comment indicates that you need a more general answer.
Most usually, the tool recommended for the general solution is 'expect'. It arranges for the command to have a pseudo-tty connected for input and output, and the command interacts with the pseudo-tty just as it would your real terminal. You tell 'expect' to send certain strings and expect certain other strings, with conditional code and regular expressions to help you do so.
Expect is built using Tcl/Tk. There are alternative implementations for other languages; Perl has an Expect module, for example.
From the man page:
-interaction mode
Sets the interaction mode. The mode can be either batchmode, nonstopmode, scrollmode, and errorstopmode. The meaning of these modes is the same as that of the corresponding \commands.
Looks like -interaction nonstopmode might help you.