Bash split file on double newline - bash

Question

I have some files with content that change from file to file.
Each file have 2 sections of lines separated by a blank line.
I never know how many lines or characters there are in either section.
The file can look something like this.
This is a file
with some text
and some more text
This code only gives the first line from each section.
awk 'BEGIN {RS="\n\n"; FS="\n";} {print $1 }' file
I need each section split up to work with.

Answer 1

Prints first part:
sed '/^$/q' test.txt
Prints second part:
sed '1,/^$/d' test.txt

Answer 2

Since this is tagged bash, might as well have a native-bash solution.
sections=( )
current_section=
while REPLY=; IFS= read -r || [[ $REPLY ]]; do
if [[ $REPLY ]]; then
# preserve newlines within the sections
if [[ $current_section ]]; then
current_section+=$'\n'"$REPLY"
else
current_section+=$REPLY
fi
else
sections+=( "$current_section" )
current_section=
fi
done <file
This will put your file's individual sections into a bash array called sections.
You can print the contents of that array like so:
printf -- '---\n%s\n---\n' "${sections[#]}"
...or iterate over it to do as you please:
for section in "${sections[#]}"; do
: do something with "$section" here
done

Answer 3

Set RS to a null/blank value to get awk to operate on sequences of blank lines.
From the POSIX specification for awk:
RS
The first character of the string value of RS shall be the input record separator; a by default. If RS contains more than one character, the results are unspecified. If RS is null, then records are separated by sequences consisting of a plus one or more blank lines, leading or trailing blank lines shall not result in empty records at the beginning or end of the input, and a shall always be a field separator, no matter what the value of FS is.

Answer 4

IFS=";"
sections=($(awk -v RS= '{print $0 ";"}' filename))
IFS=; sets the internal field separator from space (default) to a semicolon
$(awk -v RS= '{print $0 ";"}' filename) prints out sections separated by double new lines and outputs a ; after each section. Another way to achieve the same result is awk -v ORS=';' -v RS= '{print}'
sections=(awk_output_here) splits the awk output based on the IFS and assigns each section as an array element. Hence, $sections contains each section split on ;. An individual section may be accessed with ${sections[0]} where 0 is an index.
The above awk trick works because it is a use case or convention in awk.
Another technique is to have blank lines separate records. By a special dispensation, an empty string as the value of RS indicates that records are separated by one or more blank lines. When RS is set to the empty string, each record always ends at the first blank line encountered.

Answer 5

Supposing that there are precisely two parts, this very simple Perl trick will print the the standard output until it encounters an empty line, and then the remainder to error;
perl -ne 'if (1../^$/) { print STDOUT } else { print STDERR }'
e.g.
cat tmp0 | perl -ne 'if (1../^$/) { print STDOUT } else { print STDERR }' > tmp1 2> tmp2
tmp1:
This is a file
with some text
tmp2:
and some more text