Extracting part of a string to a variable in bash - string

Question

noob here, sorry if a repost. I am extracting a string from a file, and end up with a line, something like:
abcdefg:12345:67890:abcde:12345:abcde
Let's say it's in a variable named testString
the length of the values between the colons is not constant, but I want to save the number, as a string is fine, to a variable, between the 2nd and 3rd colons. so in this case I'd end up with my new variable, let's call it extractedNum, being 67890 . I assume I have to use sed but have never used it and trying to get my head around it...
Can anyone help? Cheers
On a side-note, I am using find to extract the entire line from a string, by searching for the 1st string of characters, in this case the abcdefg part.

Answer 1

Pure Bash using an array:
testString="abcdefg:12345:67890:abcde:12345:abcde"
IFS=':'
array=( $testString )
echo "value = ${array[2]}"
The output:
value = 67890

Answer 2

Here's another pure bash way. Works fine when your input is reasonably consistent and you don't need much flexibility in which section you pick out.
extractedNum="${testString#*:}" # Remove through first :
extractedNum="${extractedNum#*:}" # Remove through second :
extractedNum="${extractedNum%%:*}" # Remove from next : to end of string
You could also filter the file while reading it, in a while loop for example:
while IFS=' ' read -r col line ; do
# col has the column you wanted, line has the whole line
# # #
done < <(sed -e 's/\([^:]*:\)\{2\}\([^:]*\).*/\2 &/' "yourfile")
The sed command is picking out the 2nd column and delimiting that value from the entire line with a space. If you don't need the entire line, just remove the space+& from the replacement and drop the line variable from the read. You can pick any column by changing the number in the \{2\} bit. (Put the command in double quotes if you want to use a variable there.)

Answer 3

You can use cut for this kind of stuff. Here you go:
VAR=$(echo abcdefg:12345:67890:abcde:12345:abcde |cut -d":" -f3); echo $VAR
For the fun of it, this is how I would (not) do this with sed, but I'm sure there's easier ways. I guess that'd be a question of my own to future readers ;)
echo abcdefg:12345:67890:abcde:12345:abcde |sed -e "s/[^:]*:[^:]*:\([^:]*\):.*/\1/"

Answer 4

this should work for you: the key part is awk -F: '$0=$3'
NewVar=$(getTheLineSomehow...|awk -F: '$0=$3')
example:
kent$ newVar=$(echo "abcdefg:12345:67890:abcde:12345:abcde"|awk -F: '$0=$3')
kent$ echo $newVar
67890
if your text was stored in var testString, you could:
kent$ echo $testString
abcdefg:12345:67890:abcde:12345:abcde
kent$ newVar=$(awk -F: '$0=$3' <<<"$testString")
kent$ echo $newVar
67890