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In Unix and Unix-like operating systems, printf is a shell builtin (and utility program [2]) that formats and outputs text like the same-named C function. Originally named for outputting to a printer, it actually outputs to standard output. [3] The command accepts a format string, which specifies how to format values, and a list of values.
A stack buffer overflow can be caused deliberately as part of an attack known as stack smashing. If the affected program is running with special privileges, or accepts data from untrusted network hosts (e.g. a webserver ) then the bug is a potential security vulnerability .
printf is a C standard library function that formats text and writes it to standard output. The name, printf is short for print formatted where print refers to output to a printer although the functions are not limited to printer output. The standard library provides many other similar functions that form a family of printf-like functions.
Programmers often use tools to format programming language source code in a particular manner. Proper code formatting makes it easier to read and understand. Different programmers often prefer different styles of formatting, such as the use of code indentation and whitespace or positioning of braces.
printf(string format, items-to-format) It can take one or more arguments, where the first argument is a string to be written. This string can contain special formatting codes which are replaced by items from the remainder of the arguments. For example, an integer can be printed using the "%d" formatting code, e.g.: printf("%d", 42);
A malicious user may use the %s and %x format tokens, among others, to print data from the call stack or possibly other locations in memory. One may also write arbitrary data to arbitrary locations using the %n format token, which commands printf() and similar functions to write the number of bytes formatted to an address stored on the stack.
A common use case is in constructing printf or scanf format strings, where format specifiers are given by macros. [ 18 ] [ 19 ] A more complex example uses stringification of integers (by the preprocessor) to define a macro that expands to a sequence of string literals, which are then concatenated to a single string literal with the file name ...
In computing, Bash (short for "Bourne Again SHell,") [6] is an interactive command interpreter and command programming language [7] developed for UNIX-like operating systems.. Created in 1989 [8] by Brian Fox for the GNU Project, [9] it is supported by the Free Software Foundation [10] and designed as a 100% [11] free alternative for the Bourne shell (sh) [12] and other proprietary Unix sh