Shell Programming and Scripting

Hi experts

I want to use the parameter substitution in the bash with ## to get

a=mfs1000 (not the "mfs" maybe other string and the length is not the same"

I want to get

1000

any help? I don't know use which pattern

I use

Code:

echo ${a##*[a-b]}

It doesn't work
Lei

If what you want to do is get rid of any non-numeric characters at the start of the variable:

Code:

echo "${a##*[^0-9]}"

yes it works thank

another quesion is

a=mfs12345689

I want to get below which get rid of the no-numeric characters and the first four digital

5689

Code:

echo "${a##*[^0-9][0-9]{4}}"

it doesn't work any help

When using ${var##...}, ${var#...}, ${var%%...}, and ${var%...} the ... is a pattern. Patterns and regular expressions are similar, but not the same. This should give you what you want:

Code:

echo "${a##*[^0-9][0-9][0-9][0-9][0-9]}"

Can I say "${var##...}, ${var#...}, ${var%%...}, and ${var%...} only support the "*" "[0-9]" "[a-z]" "[A-Z", it seems others are not support " eg "." {3,}" "^" "$"

Thanks

Lei

Given the hints I've supplied so far, I'd expect that you'd be able to decode the bash man page to answer this. The example I gave above should work with any POSIX-conforming shell. I don't know of any shell where:

Code:

echo "${a##*[^0-9][0-9]{4}}"

will work. I use ksh for most of my shell programming. With ksh, but not bash:

Code:

echo "${a##*[^0-9]{4}([0-9])}"

will work.

If you can't figure out the bash man page and you don't want to restrict yourself to the set of portable shell constructs specified by the POSIX standard, you'll need to find someone else to help you.

Sorry,
Don