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Full Discussion: I am not able to use variables in system command in a C program
Top Forums UNIX for Dummies Questions & Answers I am not able to use variables in system command in a C program Post 302760631 by Corona688 on Thursday 24th of January 2013 10:42:16 AM
Old 01-24-2013
You should not use scanf to read lines, scanf has a list of problems that are too long to get into. (sscanf is safer.)

Code:
char buf[512];

fgets(buf, 512, stdin); // Read a line
if(strchr(buf, '\n')) (*strchr(buf, '\n'))=0; // Get rid of newline

// You now have a string in 'buf'.

In general, if you want to use scanf, you should use fgets to get a whole line, then use sscanf to scan the string rather than the file to avoid buffering problems.
This User Gave Thanks to Corona688 For This Post:
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LEARN ABOUT OPENDARWIN

err_error_string

ERR_error_string(3)						      OpenSSL						       ERR_error_string(3)

NAME

       ERR_error_string, ERR_error_string_n, ERR_lib_error_string, ERR_func_error_string, ERR_reason_error_string - obtain human-readable error
       message

SYNOPSIS

	#include <openssl/err.h>

	char *ERR_error_string(unsigned long e, char *buf);
	char *ERR_error_string_n(unsigned long e, char *buf, size_t len);

	const char *ERR_lib_error_string(unsigned long e);
	const char *ERR_func_error_string(unsigned long e);
	const char *ERR_reason_error_string(unsigned long e);

DESCRIPTION

       ERR_error_string() generates a human-readable string representing the error code e, and places it at buf. buf must be at least 120 bytes
       long. If buf is NULL, the error string is placed in a static buffer.  ERR_error_string_n() is a variant of ERR_error_string() that writes
       at most len characters (including the terminating 0) and truncates the string if necessary.  For ERR_error_string_n(), buf may not be NULL.

       The string will have the following format:

	error:[error code]:[library name]:[function name]:[reason string]

       error code is an 8 digit hexadecimal number, library name, function name and reason string are ASCII text.

       ERR_lib_error_string(), ERR_func_error_string() and ERR_reason_error_string() return the library name, function name and reason string
       respectively.

       The OpenSSL error strings should be loaded by calling ERR_load_crypto_strings(3) or, for SSL applications, SSL_load_error_strings(3) first.
       If there is no text string registered for the given error code, the error string will contain the numeric code.

       ERR_print_errors(3) can be used to print all error codes currently in the queue.

RETURN VALUES

       ERR_error_string() returns a pointer to a static buffer containing the string if buf == NULL, buf otherwise.

       ERR_lib_error_string(), ERR_func_error_string() and ERR_reason_error_string() return the strings, and NULL if none is registered for the
       error code.

SEE ALSO

       err(3), ERR_get_error(3), ERR_load_crypto_strings(3), SSL_load_error_strings(3) ERR_print_errors(3)

HISTORY

       ERR_error_string() is available in all versions of SSLeay and OpenSSL.  ERR_error_string_n() was added in OpenSSL 0.9.6.

0.9.7d								    2002-04-30						       ERR_error_string(3)
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