Counting characters with sed

Input:

ghw//yw/hw///??u

How can i count the slashes("/") using sed?

Don't know how to do it in sed.. but here you have AWK and Perl:

awk -F"/" '{print NF-1}' file

perl -ne '@n=m/\//g;print $#n+1' file

Using sed you still need to count, e.g.:

$ echo ghw//yw/hw///??u | sed s#[^/]##g | wc -L
6

Please explain the perl command.

Match operator (m//) returns all the matched strings as array. So @n contains all the "/"s matched in current line. $#n is index of array's last element, and because Perl starts indexing from 0, we need to add "1" to get total number of elements in array, ergo total number of "/"s in current line.

Please explain the command.

It removes all non-slash characters and then calculates the line length

# printf "%s" "ghw//yw/hw///??u" | sed 's@[^/]@@g' | wc -c
6

if in a variable, use shell expansion

A='ghw//yw/hw///??u'
echo ${A//[^\/]} | wc -L
# ${VAR//<string>} means remove every occurence of <string> in VAR
# the regex [^\/] means anything but not slash (it must be escaped by \)

s="ghw//yw/hw///??u"
s=${s//[^\/]/}
echo ${#s}

And yet another Perl one-liner:

$
$
$ echo "ghw//yw/hw///??u" | perl -lne 'print s|/||g'
6
$
$

tyler_durden

And yet another one with awk:

awk '{print gsub("/",x)}' file

miserable hack to only use sed:

#  echo ghw//yw/hw///??u | sed -e 's/\///' -e's#[^/]##g' -e 's/./x\
/g' | sed -n '$='
6

A slightly less miserable version of Tytalus' hack ;):

$ echo ghw//yw/hw///??u | sed 's/\///; y/\//\n/' | sed -n \$=
6

Regards,
Alister