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| POSIX compliant shell scripting is important if you want to write/use portable shell scripts. Basically, a generic shell script starts with:
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| #!/bin/sh
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| which in itself is a link to a shell interpreter - like bash, ksh, etc.
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| Some popular shell languages are POSIX-compliant (Bash, Korn shell), but even they offer additional non-POSIX features which will not always function on other shells.
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| '''Examples'''
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| Example for a Bash constructs that is not POSIX compliant:
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| wn_slots=4
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| for ((n=1;$n <= $wn_slots; ++n)); do
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| echo $n
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| done
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| The commands ''test expression'' is identical to the command ''[expression]'' . In fact, many sources recommend using the brackets for better readability.
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| if test "$str1" = "$str2" if ["$str1" = "$str2" ]
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| then then
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| ... ...
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| fi fi
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| '''Note''': There is also the extended test facility which is not POSIX compliant and uses double brackets.
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| I recommend the Dash shell as a very minimalistic POSIX compliant shell
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| Relevant links:
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| http://www.unix.org/single_unix_specification/
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| http://www.in-ulm.de/~mascheck/various/portability/
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| http://gondor.apana.org.au/~herbert/dash/
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