Very Computer

I am trying to put together a regexp inside of a grep statement to match
exactly one occurance of a string, but I can't quite get the syntax right. For
example, say I have the following in a file:

/usr/local/bin
/usr/local
/usr
/bin
/sbin/w

In this example, I want to only match the lines that have a single slash (/).
I've tried everything:

(e)grep '/\/{1}/' file
(e)grep "/\/{1}/" file
(e)grep '/{1}' file
(e)grep /\/{1}/ file
(e)grep "\/\{1\}" file

etc. . . .  (note that in the above I tried both grep and egrep in every
case). I have gnu grep on my linux system.

I have a feeling that even if I do get the syntax correctly, which I believe
is the case in the last attempt above, it will still match all the above lines
because the exactly one occurance is on a per pattern basis. In other words:

grep "\/\{1\}" file

would match ./foo/bar
but not ./foo//bar

I instead need something which only matches one occurance of the pattern per
line . . . How would I do this?

TIA

sean

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*/

Match the beginning of the line, followed by zero or of any character
except '/', followed by '/', followed by zero or more of any character
except '/', followed by the end of the line.

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save your old file first because this will edit the file for you:
perl -pi -e 's#.*/.*/.*##sg' filename

Sorry, I should have been more explicit in my last e-mail.  Didn't
want to be vague and am unaware of what your going to use it for.
What I posted will work but this will automatically generate backup:
perl -pi.bak -e 's#.*/.*/.*##sg' filename
and this will simply spit result to stdout from which you can pipe it
to whatever:
perl -pei 's#.*/.*/.*##sg' filename

egrep '^\/[^/]*$' filename

which matches a leading slash  ^\/
followed by  [^/]*  zero or more non-slashes up to the
end of the string $

regards
andrew

Perl style breakdown:

m:      # start match regexp
  ^     # anchor to start of line
  [^/]  # not a slash
  *     # zero or more times
  /     # a single slash
  [^/]  # not a slash
  *     # zero or more times
  $     # anchor to end of line
 :x;    # end regexp; treat as multiline regexp

Elijah
------
#!/usr/bin/perl -w

s:[^\w\s,](.*):($u=$1,$u=~s;(\w);(($s=ord($1)-97),chr((($s+$j++)%26)+97
));gex,$u):ex){}exit !print;#18/5/97:etb

"print lines beginning with zero or more characters other than
slash, followed by one slash and any number of characters
other than slashes."
--
John Savage     koala ~ sydney.dialix.com.au     <-- use this address

    grep "^[^/]*/[^/]$" $myfile

The first "[^/]*" matches a string that does not contain a slash (which
can be zero length). The "^" and the "$" anchor the string to the beginning
and end of the line.

So you're looking for:

a line that starts with a string (which can be zero length) that does not
contain a slash, then contains a slash, then ends with a string that does
not contain a slash.

With out the beginning and ending line anchors, all lines would be selected.

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[snipped message about matching lines with exactly one slash]

Quote:

>Try something like this:

>    grep "^[^/]*/[^/]$" $myfile

     Shouldn't this be [^/]* as well? Otherwise, it would only match
lines that had a slash as the second to last character...

Zach

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