How to zgrep multiple strings

Question

I am trying to zgrep multiple strings with the code below, but if I omit one of the parameters it spools a lot of un-matching files. If I enter all the 5 strings it works correctly. How can I zgrep any number of strings even if its just 3 of 5.

echo "Enter string 1: " read isdn1 echo "Enter string 2: " read isdn2 echo "Enter string 3: " read isdn3 echo "Enter string 4: " read isdn4 echo "Enter string 5: " read isdn5 for host in $(cat host.txt); do ssh "$host" "cd /onip/cdr/output/snapshot/normal/backup && zgrep '$isdn1\|$isdn2\|$isdn3\|$isdn4\|$isdn5' xyz_shot*" done 

Answer 1

if I omit one of the parameter it spools a lot of un-matching files.

Once you omit, you get an expression like || which is empty so everything matches. You have to check the input and build your expression correctly.

If the strings might also contain special characters, maybe you would prefer the --fixed-strings option of grep.

Untested:

isdn="" echo "Enter string: " while read string do [ ${#string} -eq 0 ] && break # blank line cancels isdn="$isdn$string"$'\n' done echo "You entered: " echo ---- echo -n "$isdn" echo ---- # your ssh user@host "zgrep -F '$isdn' ..." here # or maybe this would allow ' in filenames too: # echo -n "$isdn" | ssh user@host zgrep -F -f - ...