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This page is an attempt to list some of the most common bashisms ie features
not defined by POSIX (ie don't work in dash).
It probably won't be exhaustive. Note also we talk about "bashism" because this wiki is largely bash centric
but a number of these extensions work in other shells like ksh or zsh.

== Syntax ==

 * "function" is not defined by posix, only "name ()" is
 * the C-like for syntax (for (( ; ; ));do ..) is not defined by posix
 * ;;& ;& etc in case (bash4) are not defined by posix
 * the special quotes $' ' and $" " are not defined by posix
 * select is not defined by posix
 * the extended glob ( +() @( ) etc.. ) are not defined by posix
 * [^a-b] to negate a range is not defined by posix, the standard way is [!a-b]

== Expansions ==

 * Brace Expansion, eg {1..10} is not defined by posix
 * <( ) >( ) process substitution is not defined by posix

== Parameter Expansions ==

List of expansions not defined by posix:

 * ${name:n:l}
 * ${name/ }
 * ${!name}

== Arrays ==

 * arrays are not defined by posix.
 
== Conditionals ==

 * [[ is not defined by posix
 * == as an argument of test (aka [) is not defined by posix
 * < > to compare numbers as argument of test are not defined by posix, though dash implements them
 * -nt, -ot, -ef are not defined by posix
 * (( )) is not defined by posix

== Arithmetic ==

 * ++ -- are not defined by posix
 
== Redirections ==

 * >& and &> are not defined by posix
 * m>n- m<n- ie duplicating and closing a descriptor at the same time is not defined by posix
 * |& (bash4) is not defined by posix

== Builtins ==

 * echo. posix doesn't define any options, use printf
 * printf "-v" is not defined by posix. also the %b and %q format are not defined by posix
 * read, the only option defined by posix is "-r"
 * shopt, and therefore all the options it provide, extglob, nullglob, dot glob etc ..are not defined by posix

== more ==

 * [[ http://www.gnu.org/software/bash/manual/html_node/Bash-POSIX-Mode.html#Bash-POSIX-Mode | The bash manual]] has a list of the difference between bash running in posix mode and a normal bash. Note that bash in posix mode is only
guaranteed to run a shell written according to the posix specification. It doesn't mean that it will fail if you use
bashisms in your scripts.
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I really like Games Club - Dungeons and Dragons, Monopoly, Etc.!<<BR>>
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Hello!
I'm Norwegian male :).
I really like Games Club - Dungeons and Dragons, Monopoly, Etc.!

Also visit my page ... free vlc download

Bashism (last edited 2022-10-20 23:13:29 by larryv)