Get Values out of String in bash - string

Question

I hope you can help me.
I try to separate a String:
#!/bin/bash
file=$(<sample.txt)
echo "$file"
The File itself contains Values like this:
(;FF[4]GM[1]SZ[19]CA[UTF-8]SO[sometext]BC[cn]WC[ja]
What I need is a way to extract the Values between the [ ] and set them as variables, for Example:
$FF=4
$GM=1
$SZ=19
and so on
However, some Files do not contain all Values, so that in some cases there is no FF[*]. In this case the Program should use the Value of "99"
How do I have to do this?
Thank you so much for your help.
Greetings
Chris

Answer 1

It may be a bit overcomplicated, but here it comes another way:
grep -Po '[-a-zA-Z0-9]*' file | awk '!(NR%2) {printf "declare %s=\"%s\";\n", a,$0; next} {a=$0} | bash
By steps
Filter file by printing only the needed blocks:
$ grep -Po '[-a-zA-Z0-9]*' a
FF
4
GM
1
SZ
19
CA
UTF-8
SO
sometext
BC
cn
WC
ja
Reformat so that it specifies the declaration:
$ grep -Po '[-a-zA-Z0-9]*' a | awk '!(NR%2) {printf "declare %s=\"%s\";\n", a,$0; next} {a=$0}'
declare FF="4";
declare GM="1";
declare SZ="19";
declare CA="UTF-8";
declare SO="sometext";
declare BC="cn";
declare WC="ja";
And finally pipe to bash so that it is executed.
Note 2nd step could be also rewritten as
xargs -n2 | awk '{print "declare"$1"=\""$2"\";"}'

Answer 2

I'd write this, using ; or [ or ] as awk's field separators
$ line='(;FF[4]GM[1]SZ[19]CA[UTF-8]SO[sometext]BC[cn]WC[ja]'
$ awk -F '[][;]' '{for (i=2; i<NF; i+=2) {printf "%s=\"%s\" ", $i, $(i+1)}; print ""}' <<<"$line"
FF="4" GM="1" SZ="19" CA="UTF-8" SO="sometext" BC="cn" WC="ja"
Then, to evaluate the output in your current shell:
$ source <(!!)
source <(awk -F '[][;]' '{for (i=2; i<NF; i+=2) {printf "%s=\"%s\" ", $i, $(i+1)}; print ""}' <<<"$line")
$ echo $SO
sometext
To handle the default FF value:
$ source <(awk -F '[][;]' '{
print "FF=99"
for (i=2; i<NF; i+=2) printf "%s=\"%s\" ", $i, $(i+1)
print ""
}' <<< "(;A[1]B[2]")
$ echo $FF
99
$ source <(awk -F '[][;]' '{
print "FF=99"
for (i=2; i<NF; i+=2) printf "%s=\"%s\" ", $i, $(i+1)
print ""
}' <<< "(;A[1]B[2]FF[3]")
$ echo $FF
3

Answer 3

Per your request:
while IFS=\[ read -r A B; do
[[ -z $B ]] && B=99
eval "$A=\$B"
done < <(exec grep -oE '[[:alpha:]]+\[[^]]*' sample.txt)
Although using an associative array would be better:
declare -A VALUES
while IFS=\[ read -r A B; do
[[ -z $B ]] && B=99
VALUES[$A]=$B
done < <(exec grep -oE '[[:alpha:]]+\[[^]]*' sample.txt)
There you could have access both with keys ("${!VALUES[#]}") and values "${VALUES['FF']}".

Answer 4

I would probably do something like this:
set $(sed -e 's/^(;//' sample.txt | tr '[][]' ' ')
while (( $# > 2 ))
do
varname=${1}
varvalue=${2}
# do something to test varname and varvalue to make sure they're sane/safe
declare "${varname}=${varvalue}"
shift 2
done