system with variable
Hello!
Need to take variable char or string data and make system call (Linux CLI) as per above.
Please advise
const char key = "echo -n '3. Current Directory is '; pwd";
system(key);
Need to take variable char or string data and make system call (Linux CLI) as per above.
Please advise
const char key = "echo -n '3. Current Directory is '; pwd";
system(key);
So, what's your actual problem? (Presumably key should be an array in your sample).
got compilation error:
58 | const char key = "echo -n '3. Current Directory is '; pwd";
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| |
| const char*
transaction.cpp:59:9: error: invalid conversion from ‘char’ to ‘const char*’ [-fpermissive]
59 | system(key);
| ^~~
| |
| char
58 | const char key = "echo -n '3. Current Directory is '; pwd";
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
| |
| const char*
transaction.cpp:59:9: error: invalid conversion from ‘char’ to ‘const char*’ [-fpermissive]
59 | system(key);
| ^~~
| |
| char
const char* const key = "echo -n '3. Current Directory is '; pwd"; // Note: * or
const char key[] = "echo -n '3. Current Directory is '; pwd"; // Note: []
You mean std::string? Sure:
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Answer: Don’t use
Assuming C++
Assuming C
or
If you are using C you may wish to handle the (very unlikely) chance that
Hope this helps.
system() for stuff like that.Assuming C++
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Assuming C
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If you are using C you may wish to handle the (very unlikely) chance that
getcwd() will return NULL.Hope this helps.
Last edited on
| Answer: Don’t use system() for stuff like that. |
Why?
a hacker can replace the program (even the operating system ones) your program calls via system with malware of the same name. The odds of this are zero when its a personal utility program, but you cannot release a program out for others to use using this technique as the more popular it becomes, the more of a target it becomes, and its a security hazard.
that is on top of being unable to easily get errors back from it which was already stated, though you can redirect your commands to a text file and capture the output and work with it that way (clunky!).
in general, if the thing you are doing is trivial to do in standard c++, you should *learn* the c++ way and do it that way. If it is going to take a lot of code or a library, you can spawn a program (there are a half dozen ways to do that, exec, spawn, create process, system, fork, and more?) each with pros and cons.
the command you are doing is trivial in standard c++ using <filesystem> calls. Include it, look up what to do, and do that instead for this specific use case.
https://en.cppreference.com/w/cpp/filesystem/current_path
a hacker can replace the program (even the operating system ones) your program calls via system with malware of the same name. The odds of this are zero when its a personal utility program, but you cannot release a program out for others to use using this technique as the more popular it becomes, the more of a target it becomes, and its a security hazard.
that is on top of being unable to easily get errors back from it which was already stated, though you can redirect your commands to a text file and capture the output and work with it that way (clunky!).
in general, if the thing you are doing is trivial to do in standard c++, you should *learn* the c++ way and do it that way. If it is going to take a lot of code or a library, you can spawn a program (there are a half dozen ways to do that, exec, spawn, create process, system, fork, and more?) each with pros and cons.
the command you are doing is trivial in standard c++ using <filesystem> calls. Include it, look up what to do, and do that instead for this specific use case.
https://en.cppreference.com/w/cpp/filesystem/current_path
If everything you are doing winds up in a system() call, why use C++ at all? Just write a shell script. It’ll be faster and easier.
> I don't know how to convert linux commands to C++ functions.
https://linux.die.net/man/1/pwd
Scroll down to
Where a command is just a simple(ish) wrapper around some API, the manual page usually tells you some similar section 2 or section 3 function you can use in your code.
If you're not sure what you're after, apropos is your friend.
https://linux.die.net/man/1/pwd
Scroll down to
| See Also getcwd(3) |
Where a command is just a simple(ish) wrapper around some API, the manual page usually tells you some similar section 2 or section 3 function you can use in your code.
If you're not sure what you're after, apropos is your friend.
$ apropos directory alphasort (3) - scan a directory for matching entries basename (1) - strip directory and suffix from filenames bindtextdomain (3) - set directory containing message catalogs chacl (1) - change the access control list of a file or directory chdir (2) - change working directory chroot (2) - change root directory chroot (8) - run command or interactive shell with special root directory closedir (3) - close a directory cups-files.conf (5) - file and directory configuration file for cups dbus-cleanup-sockets (1) - clean up leftover sockets in a directory depmod.d (5) - Configuration directory for depmod dh_installdeb (1) - install files into the DEBIAN directory dh_testdir (1) - test directory before building Debian package dir (1) - list directory contents dirfd (3) - get directory stream file descriptor dirsplit (1) - splits directory into multiple with equal size execveat (2) - execute program relative to a directory file descriptor fchdir (2) - change working directory fdopendir (3) - open a directory File::BaseDir (3pm) - Use the Freedesktop.org base directory specification File::Listing (3pm) - parse directory listing find (1) - search for files in a directory hierarchy futimesat (2) - change timestamps of a file relative to a directory file descriptor get_current_dir_name (3) - get current working directory getcwd (2) - get current working directory getcwd (3) - get current working directory // snipped |
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