[SOLVED] special character in string variable and grep

ted_chou12 · 04-11-2011, 01:40 AM

Hi, I want to match some filename in some text, but the filenames I have no control of, so "[" can "]" can appear in the filenames:

Code:

#oh, by the way, I am using ^ and $ for matching the exact same line, so I wonder -F option disables that?
	matchname=$(echo "$basename" | sed 's/\[/\\\[/g')
	matchname=$(echo "$matchname" | sed 's/\]/\\\]/g')
	matchname=$(echo "$matchname" | sed 's/\./\\\./g')
	matchname=$(echo "$matchname" | sed 's/\{/\\\{/g')
	matchname=$(echo "$matchname" | sed 's/\}/\\\}/g')
	matchname=$(echo "$matchname" | sed 's/\(/\\\(/g')
	matchname=$(echo "$matchname" | sed 's/\)/\\\)/g')
	matchname=$(echo "$matchname" | sed 's/\+/\\\+/g')
	matchname=$(echo "$matchname" | sed 's/\-/\\\-/g')
	matchname=$(echo "$matchname" | sed 's/\</\\\</g')
	matchname=$(echo "$matchname" | sed 's/\>/\\\>/g')
	matchname=$(echo "$matchname" | sed 's/\&/\\\&/g')
	matchname=$(echo "$matchname" | sed 's/\|/\\\|/g')
	matchname=$(echo "$matchname" | sed 's/\?/\\\?/g')
	matchname=$(echo "$matchname" | sed 's/\*/\\\*/g')
if `cat "/usb/sda1/debian/mnt/sda1/dwhist.log" | grep '^'"$matchname"'$' 1>/dev/null 2>&1`  ; then
....
fi

so do I always have to use sed to addslashes to these variables before I have to grep them? and what other characters have I missed other than "[", "]", "."?
Thanks,
Ted

grail · 04-11-2011, 02:11 AM

I am not sure I am understanding the issue?
Maybe an alternate example will help, assuming I am on the right track:

Code:

#!/bin/bash

match='[na$ty fi!e n@me.t%d*]'

if grep -q "'$match'" file
then
    echo i found it
else
    echo i did not find it
fi

Throw the string without the quotes into a file some where and change the word 'file' to your filename and run script.
Seems to work just fine for me.

kurumi · 04-11-2011, 02:19 AM

Code:

$ printf "%q" "[]test[)>&]"

ted_chou12 · 04-11-2011, 02:43 AM

Hi, thanks.
@grail Sorry, not been clear, grep is treating special characters as regex syntax
@kurumi it works nicely.
Thanks

grail · 04-11-2011, 07:59 AM

Quote:

grep is treating special characters as regex syntax

Not in the one I provided, but as long as you have a solution