I am trying to complete a lab report and I have just started using linux. I am really new to this ecosystem and I don't know how most of it works. I'm slowly learning from the labscript how to compile and execute C programs. However, after executing this statement
execute the output binary file using: $ ./myapp I am a student taking CMP 310
I lost the "$" sign and whenever I pressed enter this ">" would be printed before any statement and I couldn't execute or exit. If any of you could kindly explain what I did I would really appreciate it. Thank you.
You may have pasted an unmatched quote symbol, ' or " or a backtick ` and your terminal allows you to enter multiline statement and waits until you close the quote or backtick to evaluate it. To exit the multiline mode, either enter the closing character, or hit Ctrl-C, which in this case interrupts the input.
You have to paste only this part:
./myapp I am a student taking CMP 310
It tries to execute myapp executable file in your working directory (which ./ stands for), passing to it arguments I am a student taking CMP 310.
Me reproducing your problem:
16:45 $ "I have no idea what I am doing
> wut
>
>
> hello?
>
Most probably Ctrl+C will help you.
If you are working in GUI mode (not terminal) you can just close the window and open new shell session in new window.
Related
My python script can take a series of bitwise operators as one of its arguments. They all work fine except for "=<<" which is roll left, and "=>>" which is roll right. I run my script like ./script.py -b +4,-4,=>>10,=<<1, where anything after -b can be any combination of similar operations. As soon as the terminal sees "<<" though, it just drops the cursor to a new line after the command and asks for more input instead of running the script. When it sees ">>", my script doesn't process the arguments correctly. I know it's because bash uses these characters for a specific purpose, but I'd like to get around it while still using "=>>" and "=<<" in my arguments for my script. Is there any way to do it without enclosing the argument in quotation marks?
Thank you for your help.
You should enclose the parameters that contain special symbols into single quotation marks (here, echo represents your script):
> echo '+4,-4,=>>10,=<<1'
+4,-4,=>>10,=<<1
Alternatively, save the parameters to a file (say, params.txt) and read them from the file onto the command line using the backticks:
> echo `cat params.txt`
+4,-4,=>>10,=<<1
Lastly, you can escape some offending symbols:
> echo +4,-4,=\>\>10,=\<\<1
+4,-4,=>>10,=<<1
I need test some input data flow, and use 'IO.read', but after entering data i can't exit from this mode, CTRL-Z/X/C/D doesn't help (it terminates the whole iex). So how correct EOF command for this mode?
Thanks!
TL;DR: Use ^G followed by j, i [nn] and c [nn].
In both erl and iex shells you always might ^G to enter a “User switch command” mode. Type h for help there.
iex|1 ▶ IO.read :stdio, :all
^G
User switch command
--> j
1* {erlang,apply,[#Fun<Elixir.IEx.CLI.1.96155272>,[]]}
--> i 1
--> c 1
{:error, :interrupted}
iex|2 ▶
Sidenote: the correct EOF termination would be ^D in all the terminals. I honestly have no idea why it does not work as expected in erl/iex consoles.
If I run the following:
system("screen -dmS $screenname");
it works as it should be but when I try to run a screen from perl and to execute a command (in this case tcpreplay) with some extra arguments it doesn't run as it's supposed to.
system("screen -dmS $screenname -X stuff \"`printf \"tcpreplay --intf1=eth0 s.cap\\r\"`\" ");
What am I doing wrong here?
Simo A's answer is probably right with regards to the issue, but I like to use the following when working with screen opposed to using the -X flag. Explicitly telling it the command language interpreter.
Why use -c you ask?
If the -c option is present, then commands are read from string. If there are arguments after the string, they are assigned to the positional parameters, starting with $0.
system("screen -dmS $screenname sh -c 'PRETTY MUCH ANYTHING WORKS'");
I figured I'd shared as I run alot of Perl system commands and the above always works for screen commands.
Try replacing single \" with \\\". That should do the trick.
Consider the same issue here:
system ("echo Quotation marks: \\\"here\\\" but \"not here\". ");
The output from the former line of code is: Quotation marks: "here" but not here.
Taking Simo A's answer as a starting point, I would use q( ) rather than " ".
system ( q(echo Quotation marks: \"here\" but "not here". ));
This means you don't need to escape the quote twice.
How do you compile and run Haskell on notepad++
I installed the plugin NppExec and then I pressed F6
I saved my Haskell file to C:\Users\Sam\Desktop\haskell files\new 3.hs
So on the command after I press F6 I tried typing in a few different things:
C:\Users\Sam\Desktop\haskell files\new 3.hs`
ghc.exe new 3.hs
haskell new
but I got these responses:
C:\Users\Sam\Desktop\haskell files\new 3.hs
CreateProcess() failed with error code 2:
The system cannot find the file specified.
ghc.exe new 3.hs
Process started >>>
target `new' is not a module name or a source file
<<< Process finished.
haskell new 3
CreateProcess() failed with error code 2:
The system cannot find the file specified.
================ READY ================
What is the correct way of compiling and executing at haskell file on notepad++?
You need to set NppExec to work in the current directory, so In Plugins, NppExec, tick Follow $(CURRENT_DIRECTORY).
Use the command ghc new3.hs when you press F6 (no spaces in filenames).
If you're using Haskell with stack, I found a lovely way to run things quickly using NppExec. It's a simpler process than it looks and once you do it, you're good to go:
Suppose you have a file like this in a file called yourFileName.hs:
main :: IO ()
main = putStrLn "Hello world!"
Press F6 to begin NppExec. (See Note 1 below.)
Paste the below into the window.
cd "$(FULL_CURRENT_PATH)"
stack ghci
// This is a comment you can delete. Note 2 below.
(See Note 3 below.)
Upon pressing the OK button, the Notepad++ console will run the Haskell interpreter.
Now, press F6 again. A warning menu will pop up.
Type this into the menu: :cmd return $ unlines [":l yourFileName", ":main"] and press ENTER. The file will execute. Pressing F6+ENTER will load and run the file again. When you open Notepad++ next time, this will still be there. Whenever you want to work with a new file, you will have to change yourFileName of course.
Explanation: :cmd return " . . . " allows you to execute a string as multiple ghci commands, separated by \n. unlines takes a list of strings and joins them with \n. If you don't know about $, you'll learn it soon as it's part of basic Haskell.
If you don't have a main function in your file, then instead use :cmd return $ unlines [":l yourFileName"].
Note 1: For convenience, I used the Settings > ShortCutMapper > Plugin Commands to change Execute from F6 to F1.
Note 2: If you run multiple languages in this way (like maybe Lisp?), then you can replace the // This is a comment... line with // :cmd return $ unlines [":l yourFileName", ":main"] just so you have it for later when you switch back to Haskell.
Note 3: Instead of pasting cd "$(FULL_CURRENT_PATH)" stack ghci into the NppExec window, a much simpler way to do all this is to paste stack runghc "$(FULL_CURRENT_PATH)" and nothing else needs to be done. However I found the console takes a lot longer to load and run the file in that case, so the method above is what I use.
I have a groovy file named test.groovy and have a single line of coding in it :
println args[0];
when I run this program like this groovy test ants, output is ants.
But when I run the program with the argument ants( then I'm getting error like this :
bash: syntax error near unexpected token (
1)If I escape the character ( then I'm getting the output as ants(. But why ( is needed to be escaped?
And when I run the program with the argument ant's, then clicking enter would make my terminal look like this :
>
>
>
2)And I terminate the program only using ctrl+c. What actually happens in this case? Why my terminal look like this?
3)After seeing these, what are the rules and condition that are to be followed in Groovy with accordance with Command-line arguments and the same holds for Java?
Thanks in advance.
You need to escape it as ( has a meaning in the bash shell which you are using.
The same goes for '
Try other commands:
ls (
Or
ls '
You'll get the same effect
Another option (other than escaping) is to put your arguments inside quote chars like so:
groovy test 'ants('