It knows to interpret them and won't require an -e to do so. echo prints its argument followed by a newline. In your case, assuming that blah doesn't start with a - or contain % or \, the only difference between the two commands is that echo adds a newline and printf doesn't. echo is not portable when printing variable values, as it accepts options in them. Both echo and printf are built-in commands (printf is Bash built-in since v2.0.2, 1998). David Korn realized the mistake and introduced a new form of shell quotes: $'...' which was later copied by bash and zsh but it was far too late by that time. (shebang) command 1 command 2 command 3 set -x command 4 command 5 command 6 set +x command 7 command 8 command 9 and Commands 4, 5, and 6 will be traced — unless one of them is an echo, in which case it will be executed but not traced. The behavior varies for printf '%10s\n' "$var" in multi-byte locales, there are at least three different outcomes for printf %b '\123'. Use printf (1) instead, if you need more than plain text. 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 -e option will cause echo to search for escape characters in the string and execute them. file=$(echo "$var" | tr ' ' _) is not OK in most implementations (exceptions being yash with ECHO_STYLE=raw (with the caveat that yash's variables can't hold arbitrary sequences of bytes so not arbitrary file names) and zsh's echo -E - "$var"6). They will make you ♥ Physics. When I changed my echo-heavy program from using /bin/echo to the shell's echo the performance almost doubled. The formatting strings are described in the manual page for sprintf. (NB: the last \n is necessary, echo implies it, unless you give the -n option). But remember the first argument is the format, so shouldn't contain variable/uncontrolled data. And it defined "printf" as a new, more powerful tool. Strictly speaking, you could also count that FreeBSD/macOS /bin/echo above (not their shell's echo builtin) where zsh's echo -E - "$var" or yash's ECHO_STYLE=raw echo "$var" (printf '%s\n' "$var") could be written: And zsh's echo -nE - "$var" (printf %s "$var") could be written. 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? Those specifications don't really come to the rescue here given that many implementations are not compliant. What is the difference between the printf function in bash and the echo function? That's typically what recent versions of OS/X do to build their /bin/sh. At the end of the day it's a matter of taste and requirements what you use: echo or printf. Sven Mascheck has a nice page that shows the extent of the problem. 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: For instance, some support a %q to quote the arguments but how it's done varies from shell to shell, some support \uxxxx for unicode characters. If you want a newline after the string, write printf '%s\n' "$string". https://unix.stackexchange.com/questions/58310/difference-between-printf-and-echo-in-bash/77564#77564, Couldn't verify the performance tests. Both echo and printf are built-in commands (printf is Bash built-in since v2.0.2, 1998). Internal Commands and Builtins. It offers no formatting option. Commands 7, 8, and 9 will not be traced. 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. Why wouldn't it be an advantage? sent the data. All it was doing was outputting its arguments separated by a space character and terminated by a newline character. This is a built in command that is mostly used in shell scripts and batch files to output status text to the screen or a file. In ksh93, whether echo expands escape sequences or not and recognises options depends on the content of the $PATH and/or $_AST_FEATURES environment variables. But in the end, if you stick to the POSIX feature set of printf and don't try doing anything too fancy with it, you're out of trouble. For most uses, printf is preferable. Inside ksh93, the getconf builtin (enabled with builtin getconf or by invoking command /opt/ast/bin/getconf) is the interface to astgetconf(). Benchmarks First, some background. Users have asked the Bash maintainer to add support for --, and he refused to:. Is this a difference in bash versions, or do these uses differ somehow? Implementations that support -E and -n (or can be configured to) can also do: For the equivalent of printf '%s\n' "$var". Theoretically, echo is more efficient because it does not return any value. The configuration is meant to be done via the (undocumented) astgetconf() API. (But even if command 5 is an echo, command 6 still will be traced.) If you want to add a link outside your editor, you’ll need to code it into a custom function or add it directly in a theme file. Otherwise, you could create a new widget area and add the … PDF - Download PHP for free 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. 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. Answered July 13, 2018. printf is like echo on steroids. On those echo implementations that support options, there's generally no support of a -- to mark the end of options (the echo builtin of some non-Bourne-like shells do, and zsh supports - for that though), so for instance, it's difficult to output "-n" with echo in many shells. Nowadays, echo (1) is only portable if you omit flags and escape sequences. Now, there also are differences between printf implementations. At a very high level.. printf is like echo but more formatting can be done. The difference is that echo sends a newline at the end of its output. Display a line of text containing a double quote. According to the Linux documentation, the following is the syntax for echo command. Will output it without the trailing newline character. For trivial messages (no escape sequences, no options), echo is fine. printf has more control over the output format. So while Posix encourages the use of "printf", "echo" is now standard too. Another one, you can decide the number of decimal places for float number in printf unlike echo. Previous Thread | Next Thread Will output it without the trailing newline character. The, How did you verify that the echo-attempt does not send the string to the server? No Unix/Linux implementation/distribution in their right mind would typically do that for /bin/bash though. With multiple arguments, they are separated by spaces. All in all, you don't know what echo "$var" will output unless you can make sure that $var doesn't contain backslash characters and doesn't start with -. printf, on the other hand is more reliable, at least when it's limited to the basic usage of echo. After doing that, you'll notice the $_AST_FEATURES environment variable contains UNIVERSE = att. POSIX says: if the first argument is -n or any argument contains backslashes, then the behaviour is unspecified. printf '%s' "$var". 2021 Stack Exchange, Inc. user contributions under cc by-sa, https://unix.stackexchange.com/questions/65803/why-is-printf-better-than-echo/65819#65819, A lot of early unix development happened in isolation, and good software engineering principles like, As a note, the one (and maybe only) advantage of having. Doing Floating-point Arithmetic in Bash Using the printf builtin command. 10.3.2 echo. Generating Output With echo command. It was added to more widely distributed Unix flavours with 4.3BSD-Reno and with SVR4. Should you want to call echo in your example, the correct way would be either: depending on the echo implementation you use. Bash Performance Test - Regex vs If/Else. I have heard that printf is better than echo. 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. $ echo "text with spaces" | bash -c 'printf "%q" "$(cat)"'; echo text\ with\ spaces For me, this escapes spaces with backslashes; the example in the article escapes them by quoting the whole string. printf '%s\n' "$var". The speed of both echo and print statements in PHP is roughly the same. But apparently, there are other differences, and I would like to inquire what they are as well as if there are specific cases when to use one vs the other. Concerning performance, I always had in mind that echo was faster than printf because the later has to read the string and format it. https://unix.stackexchange.com/questions/65803/why-is-printf-better-than-echo/65807#65807, https://unix.stackexchange.com/questions/65803/why-is-printf-better-than-echo/65808#65808. On some shells like bash¹ or ksh93² or yash ($ECHO_STYLE variable), the behaviour even depends on how the shell was compiled or the environment (GNU echo's behaviour will also change if $POSIXLY_CORRECT is in the environment and with the version4, zsh's with its bsd_echo option, some pdksh-based with their posix option or whether they're called as sh or not). \n for a newline character). 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)). Your wording implies that it isn't necessarily a real advantage. echo is faster on my side (bash 4.3.46). echo Command Examples And as soon as it sees \c in an argument, it stops outputting (so the trailing newline is not output either). It's not a slam dunk to always use printf. If it finds /ucb or /bsd first or if $_AST_FEATURES7 contains UNIVERSE = ucb, then it behaves the BSD3 way (-e to enable expansion, recognises -n). Echo vs Print. No new line had been printed out as it it in case of when using default setting of echo command. And, item 3 within the array points to "Apr" (remember: the first index in an array in Bash is [0]). As soon as you need something more complex, you shoud use printf which is portable (i.e. It allows programmers to break a complicated and lengthy code to small sections which can be called whenever needed. 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 The echo(1) command displays the specified text on the screen.You specify the string to display after the echo command. To print a double quote, enclose it within single … Will output the content of $var followed by a newline character regardless of what character it may contain. Actually, that's not true, the /bin/bash that Oracle ships with Solaris 11 (in an optional package) seems to be built with --enable-xpg-echo-default (that was not the case in Solaris 10). Now when a standard UNIX echo receives an argument which contains the two characters \ and t, instead of outputting them, it outputs a tab character. 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