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Diffstat (limited to 'Doc/Zsh/expn.yo')
| -rw-r--r-- | Doc/Zsh/expn.yo | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/Doc/Zsh/expn.yo b/Doc/Zsh/expn.yo index 813949222..f7343b7d1 100644 --- a/Doc/Zsh/expn.yo +++ b/Doc/Zsh/expn.yo @@ -608,6 +608,14 @@ set, the string resulting from the expansion will be interpreted as a pattern anywhere that is possible, such as in filename expansion and filename generation and pattern-matching contexts like the right hand side of the `tt(=)' and `tt(!=)' operators in conditions. + +In nested substitutions, note that the effect of the tt(~) applies to the +result of the current level of substitution. A surrounding pattern +operation on the result may cancel it. Hence, for example, if the +parameter tt(foo) is set to tt(*), tt(${~foo//\*/*.c}) is substituted by +the pattern tt(*.c), which may be expanded by filename generation, but +tt(${${~foo}//\*/*.c}) substitutes to the string tt(*.c), which will not +be further expanded. ) enditem() @@ -960,6 +968,16 @@ following steps take place where applicable at all levels of substitution. Note that, unless the `tt((P))' flag is present, the flags and any subscripts apply directly to the value of the nested substitution; for example, the expansion tt(${${foo}}) behaves exactly the same as tt(${foo}). + +At each nested level of substitution, the substituted words undergo all +forms of single-word substitution (i.e. not filename generation), including +command substitution, arithmetic expansion and filename expansion +(i.e. leading tt(~) and tt(=)). Thus, for example, tt(${${:-=cat}:h}) +expands to the directory where the tt(cat) program resides. (Explanation: +the internal substitution has no parameter but a default value tt(=cat), +which is expanded by filename expansion to a full path; the outer +substitution then applies the modifier tt(:h) and takes the directory part +of the path.) ) item(tt(2.) em(Parameter Subscripting))( If the value is a raw parameter reference with a subscript, such as |