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'''Heredoc''' syntax provides a means to delimit a string without using single or double quotes. This can be useful in situations with strings that contain many single or double quotes or that break across multiple lines. | '''Heredoc''' syntax provides a means to delimit a string without using single or double quotes. This can be useful in situations with strings that contain many single or double quotes or that break across multiple lines. |
Revision as of 18:22, 10 December 2008
indiana jones movie news emf unbelievable rental riverside video link lesbian pussy sucking movie letotro Heredoc syntax provides a means to delimit a string without using single or double quotes. This can be useful in situations with strings that contain many single or double quotes or that break across multiple lines.
EditPlus does not natively support Syntax Highlighting for heredoc strings, however you can modify an .stx file to emulate string highlighting for heredoc strings.
PHP Syntax
In PHP, <<< (three left angle brackets) is the heredoc operator, denoting the beginning of the string. This operator is followed immediately by a custom identifier, which is then used to close the heredoc string. The closing identifier must begin in the first column of the line, containing no other characters except a semicolon (;). There can be no spaces/tabs after or before the identifier or the semicolon.
The following is an example of heredoc string usage:
$str = <<<EOF Example of string spanning multiple lines using heredoc syntax. EOF; print $str;
Bash Syntax
In Bash, a here document is a special-purpose code block. It uses a form of I/O redirection to feed a command list to an interactive program or a command, such as ftp, cat, or the ex text editor. A limit string delineates (frames) the command list. The special symbol << designates the limit string. This has the effect of redirecting the output of a file into the stdin of the program or command.
The here document looks like this:
#!/bin/bash interactive-program <<LimitString command #1 command #2 ... LimitString
By default bash will interpolate the content of the block like it would in a double-quoted string. If you want to avoid this (for example if your here document contains a script you want to output verbatim) you can put single quotes around your limit string.
user@host> var="hello" user@host> cat <<LimitString user@host> echo $var user@host> LimitString echo hello user@host> cat <<'LimitString' user@host> echo $var user@host> LimitString echo $var
You can also use the following syntax to allow tab characters in front of each line. This is especially useful in scripting to allow indentation.
#!/bin/bash interactive-program <<-LimitString command #1 command #2 ... LimitString
Spaces have been used in this example due to the limitations of the Wiki editor, however it should be noted that this syntax only allows tab characters.
See also
FAQ: How do I make EditPlus "correctly" highlight PHP heredoc strings?