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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.
Two types of literal expression are usually offered: one with interpolation enabled, the other without. Non-interpolated strings may also escape sequences, in which case they are termed a raw string, though in other cases this is separate, yielding three classes of raw string, non-interpolated (but escaped) string, interpolated (and escaped) string.
When one of these command name collisions occurs, bash will by default execute a given command line using the shell built-in. Specifying a binary executable's absolute path (i.e., /bin/printf) is one way of ensuring that the shell uses a system binary.
Beyond syntactic requirements of C/C++, implicit concatenation is a form of syntactic sugar, making it simpler to split string literals across several lines, avoiding the need for line continuation (via backslashes) and allowing one to add comments to parts of strings. For example, in Python, one can comment a regular expression in this way: [21]
To demonstrate the value of the escape sequence feature, to output the text Foo on one line and Bar on the next line, the code must output a newline between the two words. The following code achieves the goal via text formatting and a hard-coded ASCII character value for newline (0x0A). This behaves as desired with the words on sequential lines ...
-s (GNU: --squeeze-blank), squeeze multiple adjacent blank lines-t implies -v, but also display tabs as ^I (GNU: -T the same, but without implying -v)-u use unbuffered I/O for stdout. POSIX does not specify the behavior without this option.-v (GNU: --show-nonprinting), displays nonprinting characters, except for tabs and the end of line character
In computing, echo is a command that outputs the strings that are passed to it as arguments. It is a command available in various operating system shells and typically used in shell scripts and batch files to output status text to the screen [ 1 ] or a computer file , or as a source part of a pipeline .
0x0A (line feed, LF, \n, ^J), moves the print head down one line, or to the left edge and down. Used as the end of line marker in most UNIX systems and variants. 0x0B (vertical tab, VT, \v, ^K), vertical tabulation. 0x0C (form feed, FF, \f, ^L), to cause a printer to eject paper to the top of the next page, or a video terminal to clear the screen.