manipulate variable string

[Patrick Stevens]

I am trying to do something I thought was simple, but has turned out to be challenge.

I have a variable length string eg xxxxHHMMSS.
I need to drop the HHMMSS. (last 6 char)

My method was to get the length of the string:
slen=`echo $string |awk '{print length($0)}'`

Then calculate a new length:
newslen=`expr $slen - 6`

Then get the string minus the last 6 char
s=`echo $string |awk '{print substr($0,0,$newslen)'`

But awk does not like the $newslen var.

Any suggestions would be welcome.

[MarkSyder · Accepted solution]

Have you declared slen and newslen as integers?

Mark Syder (like the drink but spelt different)

[Jeroen Peereboom]

Something like
str=`echo "$string" | sed 's/......$//'` should do it
(substiture any 6 chars at end of line by nothing.

JP

[curt larson_1]

try this

s=$(echo $string |
awk '{
x=length($0);
b=substr($0,1,x-6);
printf("%s",b);
}')

or to make it short

printf("%s",substr($0,1,length($0)-6));

[Sridhar Bhaskarla]

Hi,

I would do something like this.

VAR=xxxHHMMSS
TOTAL=$(echo $VAR|wc -c)
(( REST = $TOTAL - 7 ))
newVAR=$(echo $VAR|cut -c 1-${REST})
echo $newVAR

You may want to put some checks like if VAR doesn't have more than 6 char etc., etc., wc -c returns
n+1 for n chars. Hence 7 in the REST calculations.

-Sri

[curt larson_1]

or just using the shell

x=${string%??????}
s=${string#$x}

[Ralph Grothe]

Patrick,

if you're using a POSIX shell it will evaluate the string length for you

e.g.

# var=blablaHHMMSS

# echo ${#var}
12

so you could use the cut command

# echo $var|cut -c$((${#var}-5))-
HHMMSS

[curt larson_1]

the reason why what you were doing wasn't workings is that the variable newslen is defined in the shell but not to awk.

one to get the variable value into awk would be to use the -v switch to pass the value

awk -v newslen=$newslen .....

or being this is a short awk script you could play with the quotes to get the shell to do the substitution ( not recomended)

awk "{substr($0,0,$newslen);"

use double quotes instead of single quotes

[Patrick Stevens]

Thanks all, so easy but yet so hard.