diff options
Diffstat (limited to 'Etc/FAQ.yo')
| -rw-r--r-- | Etc/FAQ.yo | 143 |
1 files changed, 135 insertions, 8 deletions
diff --git a/Etc/FAQ.yo b/Etc/FAQ.yo index bd8ca977d..82053d003 100644 --- a/Etc/FAQ.yo +++ b/Etc/FAQ.yo @@ -122,6 +122,7 @@ Chapter 3: How to get various things to work 3.24. What's wrong with cut and paste on my xterm? 3.25. How do I get coloured prompts on my colour xterm? 3.26. Why is my output duplicated with `tt(foo 2>&1 >foo.out | bar)'? +3.27. What are these `^' and `~' pattern characters, anyway? Chapter 4: The mysteries of completion 4.1. What is completion? @@ -545,14 +546,8 @@ tt(EXTENDED_GLOB). option tt(KSH_GLOB) is in effect; for previous versions you must use the table above. - [1] Note that mytt(~) is the only globbing operator to have a lower - precedence than mytt(/). For example, mytt(**/foo~*bar*) matches any - file in a subdirectory called mytt(foo), except where mytt(bar) - occurred somewhere in the path (e.g. mytt(users/barstaff/foo) will - be excluded by the mytt(~) operator). As the mytt(**) operator cannot - be grouped (inside parentheses it is treated as mytt(*)), this is - one way to exclude some subdirectories from matching a mytt(**). - The form (^foo/)# also works. + [1] See question link(3.27)(327) for more on the mysteries of + mytt(~) and mytt(^). it() Unquoted assignments do file expansion after mytt(:)s (intended for PATHs). it()* mytt(typeset) and mytt(integer) have special behaviour for @@ -1452,6 +1447,8 @@ sect(Why does mytt(bindkey ^a command-name) or mytt(stty intr ^-) do something f are metacharacters. tt(^a) matches any file except one called tt(a), so the line is interpreted as bindkey followed by a list of files. Quote the tt(^) with a backslash or put quotation marks around tt(^a). + See link(3.27)(327) if you want to know more about the pattern + character mytt(^). sect(Why can't I bind tt(\C-s) and tt(\C-q) any more?) @@ -1668,6 +1665,7 @@ sect(How do I prevent the prompt overwriting output when there is no newline?) One final alternative is to put a newline in your prompt -- see question link(3.13)(313) for that. + sect(What's wrong with cut and paste on my xterm?) On the majority of modern UNIX systems, cutting text from one window and @@ -1700,6 +1698,7 @@ sect(What's wrong with cut and paste on my xterm?) fixes referred to above in order to be reliable). ) + sect(How do I get coloured prompts on my colour xterm?) (Or `color xterm', if you're reading this in black and white.) @@ -1743,6 +1742,7 @@ sect(How do I get coloured prompts on my colour xterm?) `mytt(<ESC>[0m)' puts printing back to normal so that the rest of the line is unchanged. + sect(Why is my output duplicated with `tt(foo 2>&1 >foo.out | bar)'?) This is a slightly unexpected effect of the option tt(MULTIOS), which is @@ -1780,6 +1780,133 @@ sect(Why is my output duplicated with `tt(foo 2>&1 >foo.out | bar)'?) to unset the option mytt(MULTIOS). +sect(What are these `^' and `~' pattern characters, anyway?) +label(327) + + The characters mytt(^) and mytt(~) are active when the option + tt(EXTENDED_GLOB) is set. Both are used to exclude patterns, i.e. to + say `match something other than ...'. There are some confusing + differences, however. Here are the descriptions for mytt(^) and mytt(~). + + mytt(^) means `anything except the pattern that follows'. You can + think of the combination tt(^)em(pat) as being like a tt(*) except + that it doesn't match em(pat). So, for example, mytt(myfile^.txt) + matches anything that begins with tt(myfile) except tt(myfile.txt). + Because it works with patterns, not just strings, mytt(myfile^*.c) + matches anything that begins with tt(myfile) unless it ends with + tt(.c), whatever comes in the middle --- so it matches tt(myfile1.h) + but not tt(myfile1.c). + + Also like mytt(*), mytt(^) doesn't match across directories if you're + matching files when `globbing', i.e. when you use an unquoted pattern + in an ordinary command line to generate file names. So + mytt(^dir1/^file1) matches any subdirectory of the current directory + except one called tt(dir1), and within any directory it matches it + picks any file except one called tt(file1). So the overall pattern + matches tt(dir2/file2) but not tt(dir1/file1) nor tt(dir1/file2) nor + tt(dir2/file1). (The rule that all the different bits of the pattern + must match is exactly the same as for any other pattern character, + it's just a little confusing that what em(does) match in each bit is + found by telling the shell em(not) to match something or other.) + + As with any other pattern, a mytt(^) expression doesn't treat the + character `tt(/)' specially if it's not matching files, for example + when pattern matching in a command like mytt([[ $string = ^pat1/pat2 ]]). + Here the whole string tt(pat1/pat2) is treated as the argument that + follows the mytt(^). So anything matches but that one string + tt(pat1/pat1). + + It's not obvious what something like mytt([[ $string = ^pat1^pat2 ]]) + means. You won't often have cause to use it, but the rule is that + each mytt(^) takes em(everything) that follows as an argument (unless + it's already inside parentheses --- I'll explain this below). To see + this more clearly, put those arguments in parentheses: the pattern is + equivalent to mytt(^(pat1^(pat2))). where now you can see exactly what + each mytt(^) takes as its argument. I'll leave it as an exercise for + you to work out what this does and doesn't match. + + mytt(~) is always used between two patterns --- never right at the + beginning or right at the end. Note that the other special meaning of + mytt(~), at the start of a filename to refer to your home directory or + to another named directory, doesn't require the option + tt(EXTENDED_GLOB) to be set. (At the end of an argument mytt(~) is + never special at all. This is useful if you have Emacs backup files.) + It means `match what's in front of the tilde, but only if it doesn't + match what's after the tilde'. So mytt(*.c~f*) matches any file + ending in tt(.c) except one that begins with tt(f). You'll see that, + unlike mytt(^), the parts before and after the mytt(~) both refer + separately to the entire test string. + + For matching files by globbing, mytt(~) is the only globbing operator + to have a lower precedence than mytt(/). In other words, when you + have mytt(/a/path/to/match~/a/path/not/to/match) the mytt(~) considers + what's before as a complete path to a file name, and what's after as a + pattern to match against that file. You can put any other pattern + characters in the expressions before and after the mytt(~), but as I + said the pattern after the tt(~) is really just a single pattern to + match against the name of every file found rather than a pattern to + generate a file. That means, for example, that a tt(*) after the + tt(~) em(will) match a tt(/). If that's confusing, you can think of + how mytt(~) works like this: take the pattern on the left, use it as + normal to make a list of files, then for each file found see if it + matches the pattern on the right and if it does take that file out of + the list. Note, however, that this removal of files happens + immediately, before anything else happens to the file list --- before + any glob qualifiers are applied, for example. + + One rule that is common to both mytt(^) and mytt(~) is that they can + be put inside parentheses and the arguments to them don't extend past + the parentheses. So mytt((^README).txt) matches any file ending in + tt(.txt) unless the string before that was tt(README), the same as + mytt(*.txt~README.txt) or mytt((*~README).txt). In fact, you can + always turn mytt(^something) into mytt((*~something)), where + mytt(something) mustn't contain tt(/) if the pattern is being used for + globbing. + + Likewise, mytt(abc(<->~<10-100>).txt) matches a file consisting of + tt(abc), then some digits, then tt(.txt), unless the digits happen to + match a number from 10 to 100 inclusive (remember the handy mytt(<->) + pattern for matching integers with optional limits to the range). So + this pattern matches tt(abc1.txt) or tt(abc200.txt) but not + tt(abc20.txt) nor tt(abc100.txt) nor even tt(abc0030.txt). However, + if you're matching files by globbing note you can't put mytt(/)s + inside the parentheses since the groups can't stretch across multiple + directories. (You can do that, of course, whenever the character + mytt(/) isn't special.) This means that you need to take care when + using exclusions across multiple directories; see some examples below. + + You may like to know that from zsh 5.0.3 you can disable any pattern + character separately. So if you find mytt(^) gets in your way and + you're happy using mytt(~), put mytt(disable -p "^") in tt(~/.zshrc). + You still need to turn on tt(EXTENDED_GLOB); the tt(disable) command + only deactivates things that would otherwise be active, you can't + specially enable something not allowed by the syntax options in effect. + + Here are some examples with files to illustrate the points. We'll + assume the option tt(EXTENDED_GLOB) is set and none of the pattern + characters is disabled. + + enumerate( + myeit() mytt(**/foo~*bar*) matches any file called mytt(foo) in any + subdirectory, except where mytt(bar) occurred somewhere in the path. + For example, mytt(users/barstaff/foo) will be excluded by the mytt(~) + operator. As the mytt(**) operator cannot be grouped (inside + parentheses it is treated as mytt(*)), this is one way to exclude some + subdirectories from matching a mytt(**). Note that this can be quite + inefficent because the shell performs a complete search for + mytt(**/foo) before it uses the pattern after the mytt(~) to exclude + files from the match. The file is excluded if mytt(bar) occurs + em(anywhere), in any directory segment or the final file name. + myeit() The form mytt((^foo/)#) can be used to match any hierarchy of + directories where none of the path components is tt(foo). For + example, mytt((^CVS/)#) selects all subdirectories to any depth + except where one component is named mytt(CVS). (The form + mytt((pat/)#) is very useful in other cases; for example, + mytt((../)#.cvsignore) finds the file tt(.cvsignore) if it exists + in the current directory or any parent.) + ) + + chapter(The mysteries of completion) |