[SOLVED] How to Insert characters into a string in shellscripts

Karl Godt · 11-15-2010, 01:33 PM

My problem is to insert one sign like space or ':' into a line or string.

The goal is to get a demiliter for `cut` .

For example : STR=ABCD
output should be echo $STR A B C D

I tried to do it with `tr A-Z "'A '-'Z '" and such but without success

I've read also about `sed` and `grep` :
http://unixhelp.ed.ac.uk/CGI/man-cgi?sed
http://www.linuxinfor.com/german/man1/sed.html
http://www.informatikserver.at/LHB/n...00000000000000

I guess a while read loop could do it but I don't know howto use it with ` expr length $STR`

PTrenholme · 11-15-2010, 01:44 PM

It should be simple using sed

Did you try sed 's/(.)/ \1/g;s/^ //'?

Karl Godt · 11-15-2010, 02:07 PM

Code:

# echo $STR | sed 's/(.)/ \1/g;s/^ //' 
sed: -e expression #1, char 12: invalid reference \1 on `s' command's RHS

sed syntax is very confusing to me

I have an onboard .html doc for regular expressions that isn't found in the net anymore.

Code:

sed s : stream editor substitute
/(.)  : all characters
/     : the needed space
\1    : escaped NUMBER ?
/     : closing the s command
g     : global

/^    : beginning
//    : nothing and closing the s command

I've put it in code tags for better reading

colucix · 11-15-2010, 02:12 PM

The parentheses must be escaped unless you use option -r (extended regular expressions):

Code:

sed -r 's/(.)/ \1/g;s/^ //'
sed 's/\(.\)/ \1/g;s/^ //'

Karl, maybe a good sed tutorial is worth reading: http://www.grymoire.com/Unix/Sed.html (see in particular the paragraph "Using \1 to keep part of the pattern")

Karl Godt · 11-15-2010, 02:34 PM

# echo $STR | sed 's/(.)/ \0/g;s/^ //'
ABCD
# echo $STR | sed 's/(.)/ \ 1/g'
ABCD
# echo $STR | sed 's/(.)/ 1/g'
ABCD
# echo $STR | sed 's/./ 1/g'
1 1 1 1

ooops : a new reply

Code:

# echo $STR | sed -r 's/(.)/ \1/g'
 A B C D
#

my sed must be compilied with different default options

Thank you both !!
The sed -r was exactly what I needed !