Grepping/awking assigned $variable

Question

Is it possible to grep strings or compare fields with awk in an assigned $variable.

For example

grep "word" "$foo"

only lists the complete content of $foo.

The awk command does not recognize variables but searches for a file in my folder:

awk 'FNR==NR{a[$1]++;next}a[$1]' "$foo" "$fee"

It says awk: fatal: cannot open file `$foo' for reading (No such file or directory)

@BMW suggested to provide more details. Here they are: This is the complete command:

foo=$(cat my_text.txt |  grep -B5 'application' | paste -s --delimiters=" " |sed 's/--/\n/g'| awk '{print $1 " " $2 " " $3 " " $4 " " $5}')

This is the output and the content of $foo.

• reaction_1 jj-cju 2 application
• reaction_1 jj-cju 2 application
• reaction_1 jj-cjo 2 application
• reaction_4 jj-cji 2 application
• reaction_5 jj-cju 2 application
• reaction_5 kk-cju 2 application
• reaction_7 jj-cju 2 application
• reaction_7 kk-cji 2 application
• reaction_7 kk-cji 2 application
• reaction_7 kk-cju 2 application
• reaction_7 mm-cju 2 application

Answer 1

You can do this by using a herestring in place of a filename:

grep "word" <<< "$foo"

This will work if your command only requires a single input file/variable. If you require more than one, like your example awk command, you need to use process substitution:

awk 'FNR==NR{a[$1]++;next}a[$1]' <(echo "$foo") <(echo "$fee")

The <(...) construct runs the inner commands, then the output is treated as if it is a file.

Examples:

$ echo "$foo"
first line
second line
last one

$ echo "$fee"
example
text

$ grep "line" <<< "$foo"
first line
second line

$ grep "last" <(echo "$foo")
last one

$ awk '{print NR": "$0}' <(echo "$foo") <(echo "$fee")
1: first line
2: second line
3: last one
4: example
5: text

Answer 2

If you're doing word search using awk then use:

awk -v w="word" '$0 ~ w' "$foo"

Assuming $foo is a file.

You can even use:

awk '/word/' "$foo"