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Full Discussion: If statement to compare two strings
Top Forums UNIX for Beginners Questions & Answers If statement to compare two strings Post 302999409 by Aia on Monday 19th of June 2017 10:31:48 PM
Old 06-19-2017
Quote:
Originally Posted by waince
Hi,

I am trying to do the following to see if "ip" is already present in a file.

Code:
if ["$ip" == "(cat /etc/hosts.deny | grep {$ip})"]; then
		echo "hi"
	else
		 echo "hello"
	fi

I am seeing errors on the if statement. Can someone please correct the syntax for me? Thanks
Try the following:
Code:
if grep -q "$ip" /etc/hosts.deny; then
    echo "hi"
else
    echo "hello"
fi

or

Code:
grep -q "$ip" /etc/hosts.deny && echo "hi" || echo "hello"

---------- Post updated at 08:31 PM ---------- Previous update was at 08:14 PM ----------

By the way, the errors most likely are because it needs spaces between [ and ]
Nevertheless, you are saying something you do not intend to.

The value stored in the variable ip is equal to the literal string formed with the characters (cat /etc/hosts.deny | grep {[*]value in ip variable})
Very unlikely.

[*] the ip variable will be expanded and its content will show instead.
 

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LEARN ABOUT POSIX

zgrep

ZGREP(1)						      General Commands Manual							  ZGREP(1)

NAME

       zgrep - search possibly compressed files for a regular expression

SYNOPSIS

       zgrep [ grep_options ] [ -e ] pattern filename...

DESCRIPTION

       Zgrep  invokes  grep  on  compressed  or  gzipped  files.   These  grep	options  will  cause  zgrep  to  terminate  with  an  error  code:
       (-[drRzZ]|--di*|--exc*|--inc*|--rec*|--nu*).  All other options specified are passed directly to grep.  If no file is specified,  then  the
       standard input is decompressed if necessary and fed to grep.  Otherwise the given files are uncompressed if necessary and fed to grep.

       If the GREP environment variable is set, zgrep uses it as the grep program to be invoked.

EXIT CODE

       2 - An option that is not supported was specified.

AUTHOR

       Charles Levert (charles@comm.polymtl.ca)

SEE ALSO

       grep(1), gzexe(1), gzip(1), zdiff(1), zforce(1), zmore(1), znew(1)

																	  ZGREP(1)
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