Assuming a variable contains spaces, newlines, and tabs followed by some text, why does this:
${var#"${var%%[![:space:]]*}"} # strip var of everything
# but whitespace
# then remove what's left
# (i.e. the whitespace) from var
remove the white space and leave the text, but this:
${var##[:space:]*} # strip all whitespace from var
does not?
If I set var=" This is a test ", both your suggestions do not work;
just the leading stuff is removed.
Why not use the replace functionality that removes all occurrences of whitespace and not just the first:
${var//[[:space:]]}
[:space:] is a character class. It's only valid if it is nested inside another set of [ ].
flolo's answer is documented in the "Parameter Substitution" section of the bash man page. Another source of documentation is the Parameter Substitution section of the Advanced Bash-Scripting Guide. The ABS guide includes basic documentation with excellent example code.
What about $(echo $var)
> a=" 123 456 " ; a2="$(echo $a)" ; echo "a=\"${a}\" a2=\"${a2}\""
a=" 123 456 " a2="123 456"
