How to use [[ string =~ regexp ]]?
Hello. Please CC my email to answers as I'm not subscribed to the list. I have problems using =~ operator. I've tried to search for answer, but failed. I'm using GNU bash, version 3.1.17. Can anybody give me some examples of usage? I really do not understand why $ [[ string =~ [a-z] ]] echo something something echo me something. IIUC the regular expression [a-z] matches any single letter, so how string string matches one letter? Seems that I missed the point, or did I encounter bug? Thank you for any help, Peter. signature.asc Description: This is a digitally signed message part ___ Bug-bash mailing list Bug-bash@gnu.org http://lists.gnu.org/mailman/listinfo/bug-bash
locally declared arrays do not act as arrays
Configuration Information [Automatically generated, do not change]:
Machine: i686
OS: linux-gnu
Compiler: gcc
Compilation CFLAGS: -DPROGRAM='bash' -DCONF_HOSTTYPE='i686'
-DCONF_OSTYPE='linux-gnu' -DCONF_MACHTYPE='i686-pc-linux-gnu'
-DCONF_VENDOR='pc' -DLOCALEDIR='/usr/share/locale' -DPACKAGE='bash' -DSHELL
-DHAVE_CONFIG_H -I. -I. -I./include -I./lib -O -march=pentium-m -mmmx
-mfpmath=sse -msse2 -pipe -ffast-math -funroll-loops -O3
uname output: Linux courier 2.6.11 #6 Sun May 8 23:59:20 PDT 2005 i686 unknown
unknown GNU/Linux
Machine Type: i686-pc-linux-gnu
Bash Version: 3.0
Patch Level: 16
Release Status: release
Description:
when I declare a local variable as an array it still acts as a scalar,
not as an array.
I discovered that if I seperate the local declaration from the
initialization, the variable properly acts as an array.
Repeat-By:
f() {
local B=(a b)
echo $B
C=(a b)
echo $C
}
A=(a b)
echo $A
f
Produces:
a
(a b)
a
Workaround:
split the declaration and initialization:
local B
B=(a b)
___
Bug-bash mailing list
Bug-bash@gnu.org
http://lists.gnu.org/mailman/listinfo/bug-bash
Re: How to use [[ string =~ regexp ]]?
Peter Volkov [EMAIL PROTECTED] wrote: $ [[ string =~ [a-z] ]] echo something something [a-z] matches only one charater, but the pattern is not required to match against the entire string. You can force it to match the whole string by using ^ to anchor the pattern to the beginning of the string, and $ to anchor it to the end: [[ string =~ ^[a-z]$ ]] paul ___ Bug-bash mailing list Bug-bash@gnu.org http://lists.gnu.org/mailman/listinfo/bug-bash
Re: How to use [[ string =~ regexp ]]?
On 5/21/06, Peter Volkov [EMAIL PROTECTED] wrote:
I have problems using =~ operator. I've tried to search for answer, but
failed. I'm using GNU bash, version 3.1.17. Can anybody give me some
examples of usage?
I really do not understand why
$ [[ string =~ [a-z] ]] echo something
something
echo me something. IIUC the regular expression [a-z] matches any single
letter, so how string string matches one letter?
The =~ regexp match will match a substring by default. You can use ^ and $
to anchor the expression to the start and end of the string. You
won't get a match
with
[[ string =~ ^[a-z]$ ]] echo match
But you will get a match with
[[ string =~ ^[a-z]{6}$ ]] echo match
because it matches the correct number of characters.
--
Mike Stroyan
[EMAIL PROTECTED]
___
Bug-bash mailing list
Bug-bash@gnu.org
http://lists.gnu.org/mailman/listinfo/bug-bash
Re: How to use [[ string =~ regexp ]]?
Peter Volkov wrote: Hello. Please CC my email to answers as I'm not subscribed to the list. I have problems using =~ operator. I've tried to search for answer, but failed. I'm using GNU bash, version 3.1.17. Can anybody give me some examples of usage? I really do not understand why $ [[ string =~ [a-z] ]] echo something something echo me something. IIUC the regular expression [a-z] matches any single letter, so how string string matches one letter? Seems that I missed the point, or did I encounter bug? regexec(3) returns success for that pattern, so the [[ command succeeds. I'm not sure why, unless it thinks it doesn't have to match the entire string. The real question is whether or not quoting the pattern should work as it does with other [[ pattern matching operators, which is to quote any characters special to the matching engine. I think it should, for consistency. Chet -- ``The lyf so short, the craft so long to lerne.'' - Chaucer Live Strong. No day but today. Chet Ramey, ITS, CWRU[EMAIL PROTECTED]http://cnswww.cns.cwru.edu/~chet/ ___ Bug-bash mailing list Bug-bash@gnu.org http://lists.gnu.org/mailman/listinfo/bug-bash
Re: How to use [[ string =~ regexp ]]?
Paul Jarc wrote: Peter Volkov [EMAIL PROTECTED] wrote: $ [[ string =~ [a-z] ]] echo something something [a-z] matches only one charater, but the pattern is not required to match against the entire string. You can force it to match the whole string by using ^ to anchor the pattern to the beginning of the string, and $ to anchor it to the end: [[ string =~ ^[a-z]$ ]] Paul is correct; that is the piece I was missing (I am distracted by the Cleveland-Detroit game). Chet -- ``The lyf so short, the craft so long to lerne.'' - Chaucer Live Strong. No day but today. Chet Ramey, ITS, CWRU[EMAIL PROTECTED]http://cnswww.cns.cwru.edu/~chet/ ___ Bug-bash mailing list Bug-bash@gnu.org http://lists.gnu.org/mailman/listinfo/bug-bash
Re: locally declared arrays do not act as arrays
Andrew Stitt wrote: Configuration Information [Automatically generated, do not change]: Machine: i686 OS: linux-gnu Compiler: gcc Compilation CFLAGS: -DPROGRAM='bash' -DCONF_HOSTTYPE='i686' -DCONF_OSTYPE='linux-gnu' -DCONF_MACHTYPE='i686-pc-linux-gnu' -DCONF_VENDOR='pc' -DLOCALEDIR='/usr/share/locale' -DPACKAGE='bash' -DSHELL -DHAVE_CONFIG_H -I. -I. -I./include -I./lib -O -march=pentium-m -mmmx -mfpmath=sse -msse2 -pipe -ffast-math -funroll-loops -O3 uname output: Linux courier 2.6.11 #6 Sun May 8 23:59:20 PDT 2005 i686 unknown unknown GNU/Linux Machine Type: i686-pc-linux-gnu Bash Version: 3.0 Patch Level: 16 Release Status: release Description: when I declare a local variable as an array it still acts as a scalar, not as an array. I discovered that if I seperate the local declaration from the initialization, the variable properly acts as an array. This was fixed in bash-3.1. Chet -- ``The lyf so short, the craft so long to lerne.'' - Chaucer Live Strong. No day but today. Chet Ramey, ITS, CWRU[EMAIL PROTECTED]http://cnswww.cns.cwru.edu/~chet/ ___ Bug-bash mailing list Bug-bash@gnu.org http://lists.gnu.org/mailman/listinfo/bug-bash
Re: How to use [[ string =~ regexp ]]?
Chet Ramey wrote: Peter Volkov wrote: Please CC my email to answers as I'm not subscribed to the list. $ [[ string =~ [a-z] ]] echo something something ... The real question is whether or not quoting the pattern should work as it does with other [[ pattern matching operators, which is to quote any characters special to the matching engine. I think it should, for consistency. Could you give an example of how you think it should work? (Just curious and trying to keep up.) Are you thinking that this should match: [[ string =~ [a-z] ]] echo matched || echo not matched Which this should not match? [[ string =~ [a-z] ]] echo matched || echo not matched Thanks Bob ___ Bug-bash mailing list Bug-bash@gnu.org http://lists.gnu.org/mailman/listinfo/bug-bash
Re: How to use [[ string =~ regexp ]]?
Bob Proulx wrote: Chet Ramey wrote: Peter Volkov wrote: Please CC my email to answers as I'm not subscribed to the list. $ [[ string =~ [a-z] ]] echo something something ... The real question is whether or not quoting the pattern should work as it does with other [[ pattern matching operators, which is to quote any characters special to the matching engine. I think it should, for consistency. Could you give an example of how you think it should work? (Just curious and trying to keep up.) The documentation for [[ says this about the == and != operators, which take patterns as the right-hand side: Any part of the pattern may be quoted to force it to be matched as a string. It seems reasonable that quoting any part of the rhs to the =~ operator should cause it to behave in the same manner. Since the arguments to [[ don't undergo any of the expansions that require quoting to protect them, there's no reason for =~ to act differently than the other operators that do pattern matching. Chet -- ``The lyf so short, the craft so long to lerne.'' - Chaucer Live Strong. No day but today. Chet Ramey, ITS, CWRU[EMAIL PROTECTED]http://cnswww.cns.cwru.edu/~chet/ ___ Bug-bash mailing list Bug-bash@gnu.org http://lists.gnu.org/mailman/listinfo/bug-bash
Re: How to use [[ string =~ regexp ]]?
Chet Ramey wrote: It seems reasonable that quoting any part of the rhs to the =~ operator should cause it to behave in the same manner. Since the arguments to [[ don't undergo any of the expansions that require quoting to protect them, there's no reason for =~ to act differently than the other operators that do pattern matching. That makes sense to me. Thanks for the clarification and education. Bob ___ Bug-bash mailing list Bug-bash@gnu.org http://lists.gnu.org/mailman/listinfo/bug-bash
