echo Command Examples (NB: the last \n is necessary, echo implies it, unless you give the -n option). behave the same regardless of the OS) and allows much better formatting, being designed from the same name C function. (shebang) command 1 command 2 command 3 set -x command 4 command 5 command 6 set +x command 7 command 8 command 9 and Commands 4, 5, and 6 will be traced — unless one of them is an echo, in which case it will be executed but not traced. I faced such a problem recently while writing a script. The proper way would be to monitor, https://unix.stackexchange.com/questions/58310/difference-between-printf-and-echo-in-bash/58312#58312. No new line had been printed out as it it in case of when using default setting of echo command. 2021 Stack Exchange, Inc. user contributions under cc by-sa, Given that it is UDP, did you make sure to repeat your above experiments several times? It is a good command to display a simple output when you know that the variable's contents will not cause problems. A more reliable echo can be implemented using printf, like: The subshell (which implies spawning an extra process in most shell implementations) can be avoided using local IFS with many shells, or by writing it like: With bash, at run time, there are two things that control the behaviour of echo (beside enable -n echo or redefining echo as a function or alias): There is a large set of conversion specifiers that behave the same way on all systems and in all shells. Both echo and printf are built-in commands (printf is Bash built-in since v2.0.2, 1998). Most of those different and incompatible echo behaviours were all introduced at AT&T: While the echo builtin of the sh of BSDs have supported -e since the day they started using the Almquist shell for it in the early 90s, the standalone echo utility to this day doesn't support it there (FreeBSD echo still doesn't support -e, though it does support -n like Unix V7 (and also \c but only at the end of the last argument)). Display a line of text containing a double quote. Easy and basic tutorial of PHP showing how user can print output via echo print and printf. These gave me the contrary results. Each function needs to be called by a main routine in order to run, thus, it is isolated with other parts of your code and this creates an easy way of code testing. Because different shells work differently, echo "$string" does not always print the specified string plus a newline. 10.3.2 echo. The configuration is meant to be done via the (undocumented) astgetconf() API. Its roots are in the C programming language, which uses a functionby the same name. \n for a newline character). Previous Thread | Next Thread Echo vs Print. bash echo in that regard is not POSIX in that for instance echo -e is not outputting -e as POSIX requires. No newline is added unless you specify one. Depending on the unix variant, the shell and the shell options, it may also interpret some escape sequences beginning with \, and it may treat the first argument(s) as options if they start with -. One downside of printf is performance because the built-in shell echo is much faster. Syntax : echo [option] [string] If you want to literally print the string "-e", you will have difficulties doing it with echo. Use printf (1) instead, if you need more than plain text. So while Posix encourages the use of "printf", "echo" is now standard too. Otherwise, you could create a new widget area and add the … They can appear in any order in a command in bourne-like shells. "print", on the other hand, is a non-standard feature of ksh. If you want a newline after the string, write printf '%s\n' "$string". The echo utility has been universally available for more than 4 … The default is system dependant, BSD on Debian (see the output of builtin getconf; getconf UNIVERSE in recent versions of ksh93): The reference to BSD for the handling of the -e option is a bit misleading here. That's typically what recent versions of OS/X do to build their /bin/sh. Concerning performance, I always had in mind that echo was faster than printf because the later has to read the string and format it. To print a new line we need to supply printf with format string with escape sequence \n ( new line ): $ printf "%s\n" "hello printf" hello printf The format string is applied to each argument: $ printf "%s\n" "hello printf" "in" "bash script" hello printf in bash script Format specifiers A function, also known as a subroutine in programming languages is a set of instructions that performs a specific task for a main routine . They then thought harder but instead of adding that functionality to the shell (like perl where inside double quotes, \t actually means a tab character), they added it to echo. printf "k\\nk" printf 'k\\nk' 3. Why wouldn't it be an advantage? printf has more control over the output format. Even if you're already familiar with the printf command, if you got your information via "man printf" you may be missing a couple of useful features that are provided by bash's built-in version of the standard printf(1) command.. (But even if command 5 is an echo, command 6 still will be traced.) echo [option(s)][string(s)] Now, we shall see the different ways in which we can output the text on the terminal. These two commands which are mainly used to place output information to the visitor’s screen, such as like in the web page give the same action. The _AST_FEATURES is not meant to be manipulated directly, it is used to propagate AST configuration settings across command execution. Answered July 13, 2018. printf is like echo on steroids. $ echo "text with spaces" | bash -c 'printf "%q" "$(cat)"'; echo text\ with\ spaces For me, this escapes spaces with backslashes; the example in the article escapes them by quoting the whole string. It is a handy way to produce precisely-formatted output from numerical or textual arguments. Generating Output With echo command. Could you expand on that? Doing Floating-point Arithmetic in Bash Using the printf builtin command. But testing them with time (also built-in) the results say otherwise: Telling printf to add newline characters, just as echo does by default: that is obviously slower than without printing the \n, but yet faster than echo. And it defined "printf" as a new, more powerful tool. :-/, Same thing, echo is faster (GNU bash, version 4.3.33(1)-release). https://unix.stackexchange.com/questions/65803/why-is-printf-better-than-echo/159115#159115, But many of those printf implementations are broken. did not send the "blah" command to the server listening on 8125, whereas. If I replace echo with printf, will it introduce any side effects (because of the >&2)? Will output the content of $var followed by a newline character regardless of what character it may contain. If $PATH contains a component that contains /5bin or /xpg before the /bin or /usr/bin component then it behave the SysV/UNIX way (expands sequences, doesn't accept options). If you didn't know bash had its own version of printf, then you didn't heed the note in the man page for the printf(1) command: Lectures by Walter Lewin. echo vs printf January 12, 2019 January 12, 2019 jack4it In bash, or generally the family of shell languages, echo and printf are often used to output messages to the screen (or terminal, or tty, or stdout, to earn a few more geek points…). The echo(1) command displays the specified text on the screen.You specify the string to display after the echo command. To really represent the current reality, POSIX should actually say: if the first argument matches the ^-([eEn]*|-help|-version)$ extended regexp or any argument contains backslashes (or characters whose encoding contains the encoding of the backslash character like α in locales using the BIG5 charset), then the behaviour is unspecified. For instance, you'd do builtin getconf; getconf UNIVERSE = att to change the UNIVERSE setting to att (causing echo to behave the SysV way among other things). Interpreting a variable as its value is one way of expanding it, but there are a few more you can leverage. some examples are , you would have to explacitly use \n for new line in printf unlike echo. printf '%s\n' "$var". In the below-mentioned case, when ${array[0]} is enclosed within single quotes, it gets evaluated and 10 is printed, as it is the 0th element of the array but when enclosed within single quotes, the literal identity of $ is retained and it does not get evaluated. posix mode can be enabled if bash is called as sh or if POSIXLY_CORRECT is in the environment or with the the posix option: xpg_echo expands sequences as UNIX requires: This time, bash is both POSIX and UNIX conformant. The >&2 part has nothing to do with either echo nor printf.The >& is a shell redirection operator, where in this case it duplicates stdout (implied, though could be referenced explicitly with 1>&2) of the command to stderr ( file descriptor 2). The UNIX specification is stricter, it prohibits -n and requires expansion of some escape sequences including the \c one to stop outputting. echo is not portable when printing variable values, as it accepts options in them. https://unix.stackexchange.com/questions/58310/difference-between-printf-and-echo-in-bash/77564#77564, Couldn't verify the performance tests. You can pass the -n option to suppress the printing of the newline. One "advantage", if you want to call it that, would be that you don't have to tell it like echo to interpret certain escape sequences such as \n. Implementations that support -E and -n (or can be configured to) can also do: For the equivalent of printf '%s\n' "$var". So what that means is that you can't use echo to display uncontrolled data. printf prints a formatted string to the standard output. Why the scare quotes? This comes into play particularly in Cygwin where each instance of a new command causes heavy Windows overhead. env echo -n outputs nothing instead of -n, env echo '\n' outputs \n instead of . Is this a difference in bash versions, or do these uses differ somehow? Additionally, functions can be called anytime and repeatedly, this allows you reuse, optimize and minimi… It's not a slam dunk to always use printf. Any code that would use `echo --' is, by definition, new code and new code should use printf. echo is faster on my side (bash 4.3.46). Using one over the other is not likely to yield any performance improvement in your application. Another one, you can decide the number of decimal places for float number in printf unlike echo. In the first argument, all characters except two are interpreted literally: % starts a printf specifier, and \ starts an escape sequence (e.g. Probably, if you add the newline character that echo uses by default (except when using -n option) you'll get the same effect. Send Text to Standard Output. echo prints its argument followed by a newline. Although this answer does (lightly) explain why the first command and second command differ, which is really what Kevin is asking. Will output it without the trailing newline character. For most uses, printf is preferable. Other shells/Unix vendors/versions chose to do it differently: they added a -e option to expand escape sequences, and a -n option to not output the trailing newline. Some have a -E to disable escape sequences, some have -n but not -e, the list of escape sequences supported by one echo implementation is not necessarily the same as supported by another. 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