I'm writing a utility that accepts a secondary shell command as its final parameter. My utility then runs the supplied shell command on behalf of the user. The user will invoke it as follows:
util [options] command with args
I want QCommandLineParser to parse the initial options, then leave the tail-end stuff alone (or parse it into a pure value list). Instead, QCommandLineParser complains that the user has entered invalid arguments.
For example, if the user were to enter
util -r ls -l
then ls -l is a valid command that I want to accept but Qt tells the user that -l is an invalid argument for my application. What's the best way to deal with this?
Related
I am trying to launch a legacy application in GDB, and it requires that it's argv[0] value not contain anything other than alphanumeric characters.
Whenever I launch the program in GDB it seems that it expands the name to be the full path before running the program, so I get an error like (because it can't deal with the slashes):
"Cannot find /home/user/myapp ..."
Is it possible to run a program in GDB with a relative path, so that it will just see "myapp"?
Gdb normally runs target commands using the shell command line
exec program_pathname program_arguments
But it has a set exec-wrapper command that will change this to
exec exec_wrapper program_pathname program_arguments
The exec_wrapper is often another command, but it can be an option that the exec command accepts.
Many shells (bash, zsh, ksh93) support a -a option to the exec command to set argv[0].
So, if your shell supports exec -a, you can do the following to invoke /home/user/myapp with argv[0]==myapp:
(gdb) set exec-wrapper -a myapp
Trying to trigger scans from fujitsu ScanSnap iX500 using CLI, defining a specific scanner.
scanimage --device 'fujitsu:ScanSnap iX500:[s/n]' --resolution 300 --batch=Scan-p%d.pnm --format=pnm --mode color
The error from that: scanimage: open of device fujitsu:ScanSnap iX500:[s/n] failed: Invalid argument
The --device entry was derived from sudo scanimage -L
The following variations of --device return the same error:
fujitsu:ScanSnap iX500
fujitsu:ScanSnap
fujitsu
Removing the --device option removes the error, BUT causes the command to search for a locally-attached device, which introduces a long delay. Targeting the --device in the hopes of eliminating the delay.
From https://linux.die.net/man/1/scanimage : there is no parameter "--device" for the scanimage command.
Maybe you want to use -d or --device-name and follow the advices given in the manual:
The -d or --device-name options must be followed by a SANE device-name like 'epson:/dev/sg0' or 'hp:/dev/usbscanner0'. A (partial) list of available devices can be obtained with the --list-devices option (see below). If no device-name is specified explicitly, scanimage reads a device-name from the environment variable SANE_DEFAULT_DEVICE. If this variable is not set, scanimage will attempt to open the first available device.
The problem, it turns out, was not in the naming of the device. (The name returned by sudo scanimage -L is the correct one to use and works fine.
The issue has to do with permissions / user
Running the command under the .sh file used appropriate permissions. Running directly in command line must have used another user, even though both were executed under the same ssh session.
Solution: Choose the right login user. In my case adding sudo before the command (which was not included or necessary in the .sh file) resolved the issue.
Well, I will put it plain and simple: I am a C++ pleb. Still trying to learn though.
My question is: is it possible to run a command though the terminal using system() command without letting the command be shown in the console/terminal?
Example:
system("sudo service sshd start") ;
Output: Sudo service sshd start
Where as I want:
system("sudo service sshd start") ;
output: (Blank)
Note: I am on linux.
The system standard library function starts up a subshell and executes the provided string as a command within that subshell. (Note that a subshell is simply a process running a shell interpreter; the particular shell interpreter invoked by system will depend on your system. No terminal emulator is used; at least, not on Unix or Unix-like systems.)
The system function does not reassign any file descriptors before starting the subshell, so the command executes with the current standard input, output and error assignments. Many commands will output to stdout and/or stderr, and those outputs will not be supressed by system.
If you want the command to execute silently, then you can redirect stdout and/or stderr in the command itself:
system("sudo service sshd start >>/dev/null 2>>/dev/null") ;
Of course, that will hide any error messages which might result from the command failing, so you should check the return value of system and provide your own error message (or log the information) if it is not 0.
This really has very little to do with the system call or the fact that you are triggering the subshell from within your own executable. The same command would have the same behaviour if typed directly into a shell.
I recently decided to start teaching myself C++ and thought a simple encryption project would be a good place to start, since it covers most of the basics (cout, cin, opening files, etc). Is there a way to have the code open a terminal window similar to the one opened when I compile and run from sublime text?
I have tried this so far, but it hasn't changed anything.
string cmd = "gnome-terminal-x sh-c 'ls-l; exec bash'";
system(cmd.c_str());
Essentially, I would like to be able to run the program by clicking the .exe, and have the terminal where all of the input and output goes pop up.
You don't need to write any code, you just need to configure the shortcut to launch the program in a terminal. Here's a Gnome dialog that shows that option:
Problem seems to be gnome-terminal, or then just my failure to give it the right arguments. For example gnome-terminal -x sh -c 'ls -l ; exec bash' from command line in another terminal just opens an empty gnome-terminal and spits out a bunch of glib warnings to original terminal... (Note to readers: if you can give the right command that works for gnome-terminal, please let me know in comments or just edit this paragraph.)
However, using xterm works, for example xterm -e sh -c 'ls -l; exec bash', or a line for your code:
string cmd = "xterm -e sh -c 'ls -l; exec bash'";
As a side note, the command to open the default x terminal window of the DE is x-terminal-emulator, but it quite often has the practical problem of different terminals taking different arguments, so sadly you're probably better of using a specific terminal, like that xterm, and requiring that to be installed, or letting user to configure what terminal to use, with what arguments (though letting user to specify any command to be run can also be a security risk, if user is not always trusted).
Just be very careful with escaping. For example, when you test the command form command line, and then copy-paste it to C++ string literal, you need to escape every " and \ one more time for C++. If you have trouble with this, check out C++11 raw strings.
Escaping becomes extra important if you construct the command string at runtime, and especially if you accept user input and add that to the string. In that case, better search for and use some existing library like GLib, or sanitize the user input very carefully (ie. just paranoidically reject anything with chars, which may have a special meaning in shell in some context).
If you are actually asking, how can my program open a console window for itself similar to how Windows console programs behave, and redirect it's own stdin, stdout and stderr there, as if it was launched from command line, that that is not very easy from the same binary, and it is not commonly done like that in Unix.
If you want a behaviour like that, you could create a desktop shortcut, but more general way is to write a wrapper shell script, which starts your binary in a terminal. What kind of script exactly, depends on how you want it to behave exactly: what will it do with stdio, will it return or wait for program to exit, how do you want it to find the binary, how does it behave when run from command line instead of double-clicking from GUI, etc.
I have a question regarding executing shell commands in c++. I'm building an application in winforms, vs 2008. My application has a button, when clicked should decode a binary file to a .csv file. I can decode files by first going to the right directory (cd Test_Copy2) and then execute a command in the command prompt (java -jar tool.jar -b x.fit x.csv). I tried a lot of different stuff but unfortunately got none to work!
I tried using:
system, _popen, ShellExecute(NULL, L"open", L"C:\\WINDOWS\\system32\\cmd.exe ", L"java -jar Tool.jar -b x.fit x.csv", L"C:\\Test_Copy2", SW_SHOWNORMAL)
Can anyone please provide me with an example on how to do that? I dont know where I'm going wrong, most of the time the command prompt opens but no command is executed!
If you really want to run the jar in a cmd.exe instance, you need to add one of the correct command line switches to cmd.exe for it to work the way you want it to:
/C Carries out the command specified by string and then terminates
/K Carries out the command specified by string but remains
For instance, your command string should be:
C:\\WINDOWS\\system32\\cmd.exe /c java -jar Tool.jar -b x.fit x.csv
You can use the system() function to execute shell commands.
For example:
system("DIR") executes the DIR command in the CMD shell. The default directory at the start is the directory you're .exe file is located.
'system("PAUSE")` executes the PAUSE command.
The command/s you wannt to execute should be passed as a constant string to the function.
Edit:
For you paritcular program the syntax (IMO) would be:
system("java -jar Tool.jar -b x.fit x.csv")