This question already has answers here:
Closed 11 years ago.
Possible Duplicate:
Best way to capture stdout from a system() command so it can be passed to another function
In linux to get the current status of a service I wrote this code segment::
char cmd[100];
sprintf(cmd,"service %s status",argv[1]);
system(cmd);
It is running fine and it shows the output on the console like : mysql is running OR mysql is stopped
But I need this console output in a string variable. How can I get 'mysql is running' in a string variable so that I can use this string variable later.
thankx.
If you want to capture output then use popen() rather than system().
Related
This question already has answers here:
GDB: How to remove a variable from the auto display
(2 answers)
Closed 5 years ago.
I am working on a c++ program on linux ubuntu 16.04 and I've done a tutorial on gnu debugger.
I am having some problems with my code and as I step through it it's easier for me to compare two variables at each part fullPath and argv[1]
But once I get past that particular segment I want to remove argv[1].
I called them with the following:
display argv[1]
display fullPath
But when I try to remove argv[1] with undisplay argv[1] I get an error that reads the following:
warning: bad display number at or near 'argv[1]'
It still continues to display argv[1] unless I exit debugger and start it again without displaying it. Is there a way to fix this?
NOTE
I've also tried delete argv[1] which also doesn't work.
The undisplay command is expecting a list number, not an expression. You can see the list numbers for all your auto-display expressions by typing:
info display
Let's say that argv[1] is assigned item 3 in that list. You would then remove it with:
undisplay 3
This question already has answers here:
Running shell command and capturing the output
(21 answers)
Closed 6 years ago.
I was trying to scan ble devices using hcitool lescan in a python code. The hcitool lescan works well on the command line but fails to return any output using subprocess.Popen.The code works fine when lescan is replaced with 'scan' ie scan of conventional bluetooth.
My code is:
import os
import time
import subprocess
proc = subprocess.Popen(['sudo','timeout', '20s','hcitool', 'lescan'],stdout=subprocess.PIPE)
proc.wait()
lines = proc.stdout.readlines()
print lines
Have you tried to use communicate?
proc = subprocess.Popen(...)
stdout, stderr = proc.communicate()
Use
from commands import getoutput as shell
s = shell('hcitool scan')
s is a string with what you are looking for.
This question already has an answer here:
how to run a batch file using c++?
(1 answer)
Closed 8 years ago.
I want to run an .exe file from my c++ program.
but I also want to pipe an input file and take output of that file into another file.
I know that this can be done from command line as:
c:> my_program.exe <"input.txt"> "output.txt"
with this command, my_program takes all standard input from input.txt and gives standard output to output.txt
Now I want this should happen from my C++ program.
my my_program.exe is in D: drive. also input.txt is in D: drive.
Please tell me how can I accomplish my goal.
You need to handle input and output pipes inside your c++ program, and read/write data to files accordingly. See MSDN for example.
The question was basically how to redirect stdin and stdout from the inside of C++, which as been answered here.
Just change your directory to D:
cd D:\
D:>my_program.exe <"input.txt">"output.txt"
This question already has answers here:
How do I execute a command and get the output of the command within C++ using POSIX?
(12 answers)
How to assign shell command output to a variable in C language
(4 answers)
Closed 9 years ago.
I want to execute a script through a c++ program and get its output. Presently I am doing
system("./script.sh > out.txt");
But I need a command that get the output to a string, some thing like:
out = system("./script.sh");
printf(out);
I can't read the file out.txt after execute the script because I don't have permission to that. I deployed my c++ program at other framework (boinc) that doesn't give me this permission.
Does anybody have a hint?
Thanks in advance!
Felipe
you can use popen() and then get the output of the command from the pipe opened by popen()
FILE *fp;
fp=popen("./script.sh","r");
and to get your output. you can use fgets() or fread() to read from pipe like you read from a file
This question already has answers here:
Closed 11 years ago.
Possible Duplicate:
Detect if stdin is a terminal or pipe in C/C++/Qt?
I'm writing a command line application that expects data as either a command line argument, or from cin.
Is there a way to check if the user piped some data in the application ($ ./myapp < test.txt), and only display a prompt for keyboard input if not?
If I'm checking for !cin.good() / cin.eof() etc., the prompt will never appear.
isatty(STDIN_FILENO)
will return whether standard input is a terminal (tty), i.e. interactive.
Perhaps you can do something with fstat(2) and S_ISFIFO?