It's a trade off between portability and performance. That means that echo ${month[3]}, after the expansion, translates to echo "Apr". That's typically what recent versions of OS/X do to build their /bin/sh. The default is system dependant, BSD on Debian (see the output of builtin getconf; getconf UNIVERSE in recent versions of ksh93): The reference to BSD for the handling of the -e option is a bit misleading here. It allows programmers to break a complicated and lengthy code to small sections which can be called whenever needed. Will output it without the trailing newline character. Benchmarks First, some background. At a very high level.. printf is like echo but more formatting can be done. sent the data. One downside of printf is performance because the built-in shell echo is much faster. Syntax : echo [option] [string] Both echo and printf are built-in commands (printf is Bash built-in since v2.0.2, 1998). Concerning performance, I always had in mind that echo was faster than printf because the later has to read the string and format it. Repeated the results with GNU bash 4.4.12(1), and I've got different results: https://unix.stackexchange.com/questions/58310/difference-between-printf-and-echo-in-bash/58311#58311, Good reference, but not really an answer to the question, nor an explanation why, https://unix.stackexchange.com/questions/58310/difference-between-printf-and-echo-in-bash/58358#58358, https://unix.stackexchange.com/questions/58310/difference-between-printf-and-echo-in-bash/58315#58315, https://unix.stackexchange.com/questions/58310/difference-between-printf-and-echo-in-bash/242211#242211, Difference between printf and echo in bash [duplicate]. And, item 3 within the array points to "Apr" (remember: the first index in an array in Bash is [0]). Nowadays, echo (1) is only portable if you omit flags and escape sequences. One "advantage", if you want to call it that, would be that you don't have to tell it like echo to interpret certain escape sequences such as \n. Because different shells work differently, echo "$string" does not always print the specified string plus a newline. 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 difference is that echo sends a newline at the end of its output. 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. Note that in POSIX mode, bash is still not POSIX conformant as it doesn't output -e in: The default values for xpg_echo and posix can be defined at compilation time with the --enable-xpg-echo-default and --enable-strict-posix-default options to the configure script. The _AST_FEATURES is not meant to be manipulated directly, it is used to propagate AST configuration settings across command execution. 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). https://unix.stackexchange.com/questions/58310/difference-between-printf-and-echo-in-bash/77564#77564, Couldn't verify the performance tests. Generating Output With echo command. Speed of echo vs print in PHP . 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 did not send the "blah" command to the server listening on 8125, whereas. I can recall only one instance from my experience where I had to use printf because echo didn't work for feeding some text into some program on RHEL 5.8 but printf did. Since coreutils 8.31 (and this commit), GNU echo now expands escape sequences by default when POSIXLY_CORRECT is in the environment, to match the behaviour of bash -o posix -O xpg_echo's echo builtin (see bug report). PDF - Download PHP for free GitHub Gist: instantly share code, notes, and snippets. echo is useful when it comes to printing the value of a variable or a (simple) line, but that's all there is to it. This video also discuss about their differences. printf was introduced with the Ninth Edition System (reference in SUSv3). 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? Will output it without the trailing newline character. Internal Commands and Builtins. They will make you ♥ Physics. Use printf (1) instead, if you need more than plain text. 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. It is a handy way to produce precisely-formatted output from numerical or textual arguments. There is no way to "send" an EOF. Bash Performance Test - Regex vs If/Else. 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…). According to the Linux documentation, the following is the syntax for echo command. It's not; echo has never behaved this way. echo is not portable when printing variable values, as it accepts options in them. Echo is a statement in which it does not return the valueprint. Display a line of text containing a double quote. The configuration is meant to be done via the (undocumented) astgetconf() API. Previous Thread | Next Thread 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. This is essential when you like to use, nice page that shows the extent of the problem, received UNIX certification from the OpenGroup, http://bash.cyberciti.biz/guide/Echo_Command. 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. 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. Will output the content of $var followed by a newline character regardless of what character it may contain. 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