How to check for strings between certain strings in unix scripting?

Question

String:

name@gmail.com

Checking for:

@
.com

My code

if [[ $word =~ "@" ]] 
then 
    if [[ $word =~ ".com" || $word =~ ".ca"  ]]

My problem

name@.com

The above example gets passed, which is not what I want. How do I check for characters (1 or more) between "@" and ".com"?

score 3 · Accepted Answer · edited May 23 '17 at 10:31

3

You can use a very very basic regex:

[[ $var =~ ^[a-z]+@[a-z]+\.[a-z]+$ ]]

It looks for a string being exactly like this:

at least one a-z char
@
at least one a-z char
.
at least one a-z char

It can get as complicated as you want, see for example Email check regular expression with bash script.

See in action

$ var="a@b.com"

$ [[ $var =~ ^[a-z]+@[a-z]+\.[a-z]+$ ]] && echo "kind of valid email"
kind of valid email

$ var="a@.com"
$ [[ $var =~ ^[a-z]+@[a-z]+\.[a-z]+$ ]] && echo "kind of valid email"
$

edited May 23 '17 at 10:31

Community

1
1

answered Mar 19 '14 at 13:50

fedorqui

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Sorry, but do you think you can explain further? I don't understand what ^[a-z]@[a-z].[a-z] is doing. And what the && is doing, outside of the brackets – Dan Mar 19 '14 at 13:53
1

Use `\.` to match a literal `.` – mklement0 Mar 19 '14 at 13:54
1

@Dan sure, just updated my answer with a proper explanation. The `[[ condition ]] && echo "hello"` perform the `echo` in case the `[[ ]]` is true. So this way you can check if you are entering in the `if` condition. – fedorqui Mar 19 '14 at 13:55

score 1 · Answer 2 · answered Mar 19 '14 at 13:59

1

why not go for other tools like perl:

> echo "x@gmail.com" | perl -lne 'print $1 if(/@(.*?)\.com/)'
gmail

answered Mar 19 '14 at 13:59

Vijay

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score 1 · Answer 3 · answered Mar 19 '14 at 15:29

The glob pattern would be: [[ $word == ?*@?*.@(com|ca) ]]

? matches any single character and * matches zero or more characters

@(p1|p2|p3|...) is an extended globbing pattern that matches one of the given patterns. This requires:
shopt -s extglob

testing:

$ for word in @.com @a.ca a@.com a@b.ca a@b.org; do
    echo -ne "$word\t"
    [[ $word == ?*@?*.@(com|ca) ]] && echo matches || echo does not match
done
@.com   does not match
@a.ca   does not match
a@.com  does not match
a@b.ca  matches
a@b.org does not match

How to check for strings between certain strings in unix scripting?

3 Answers3

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