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problem in string comparison in shell programming

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# 8  
Old 02-26-2009
Quote:
Originally Posted by fpmurphy
Just a quick note - the string comparison is based on the ASCII value of the characters in the string and may fail for strings containing non-ASCII characters.

It should work for any values. It compares "lexicographically in the current locale".
# 9  
Old 02-27-2009
Quote:
It should work for any values. It compares "lexicographically in the current locale".
Not necessarily true. It will result in an unsatisfactory ordering for certain locales unless the correct collator (for the locale) is provided in the underlying OS to allow locale-sensitive ordering. Bash and other shells do not include built-in collators.

Some shells such as ksh93 and zsh specifically avoid the issue for this reason. From the ksh93 man page
Quote:
string1 < string2
True, if string1 comes before string2 based on ASCII value of their characters.
string1 > string2
True, if string1 comes after string2 based on ASCII value of their characters.
The zsh manual has almost identical text.
# 10  
Old 02-27-2009
Quote:
Originally Posted by fpmurphy
Not necessarily true. It will result in an unsatisfactory ordering for certain locales unless the correct collator (for the locale) is provided in the underlying OS to allow locale-sensitive ordering. Bash and other shells do not include built-in collators.

Some shells such as ksh93 and zsh specifically avoid the issue for this reason. From the ksh93 man page

The zsh manual has almost identical text.

The bash manual states, "lexicographically in the current locale", but in fact uses the character's ASCII value.

The shell does use the locale's collating order for character ranges, e.g., [a-z]. I don't know whether the order is generated by the shell or by the OS.
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