Use grep in array

Question

Below is the script to find specific array of different words "bots,spyware,virus" in file, if file exists.

#!/bin/bash

#strings to find in file
NAME[0]="bots"
NAME[1]="spyware"
NAME[2]="virus"

#location of file
LOGS=/home/testing.txt

#define function to grep any of the above mentioned array strings in file
func(){
if `grep "${NAME[*]}" $LOGS`; then
echo "CRITICAL: ${NAME[*]}"
else
echo "errors not found"
exit
fi
}

#file exist or not exist
if [ -f $LOGS ]; then
   echo " File Found"

  #call functions
  func
  modified

  else
   echo "File Not Found"
   exit

But grep "${NAME[*]}" $LOGS does not work. It shows below error:

grep: virus: No such file or directory
grep: bots: No such file or directory

learn to use set -x to turn on debugging trace of shell script (set +x to turn off). And you'll discover you need to convert your arr into a search target that looks like grep 'a|b|c' file. And great 2nd Q, but we only need to see the func() code, so learn to target your Qs to the non-working code. Good luck. — shellter
– shellter, Commented Oct 8, 2016 at 12:52

Socowi · Accepted Answer · 2016-10-08 14:16:58Z

Here is the solution for the problematic part.

Go to if-body when grep finds at least one entry of the array KEYWORDS in file FILE.
The following code works for array entries with special characters like space or *.

KEYWORDS[0]="virus"
KEYWORDS[1]="two words"
KEYWORDS[2]="special chars .+*?|()[]^&"

if grep -qF "${KEYWORDS[@]/#/-e}" -- "$FILE"; then
    # found a keyword
fi

What happens here?

grep -q
Do not output anything. Exit on the first match. We don't have to scan the complete file if we already found a keyword.
grep -F
Search fixed strings. Characters like *, |, or + lose their special meaning.
"{KEYWORDS[@]}"
Each entry of the array expands to one quoted string. Here "virus" "two words" "special chars .+*?|()[]^&"
"${KEYWORDS[@]/#/-e}"
Prepend -e to every entry of the array. Grep can search for multiple patterns using this option. grep -e"FirstPattern" -e"SecondPattern" ...
grep Pattern -- "$FILE"
The -- is a hint, that "$FILE" should be interpreted as a file name. Its possible to name a file -eFunny, which would stop our script, because grep would think that no filename was provided and would wait for input from stdin. Its not really necessary here, but a good habit to establish. The so called double dash is available for most commands, not just grep.

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