Compare output rather than command

Question

Trying to create a script to read a remote file and check the md5 checksum and alert if a mismatch yet getting an error I can't understand.

#!/bin/sh
REMOTEMD5=$(ssh user@host 'md5sum file.txt')
LOCALMD5=$(md5sum 'file.txt')
if [$LOCALMD5 !== $REMOTEMD5]
then
  echo "all OK"
else
  echo -e "no match, Local:"$LOCALMD5"\nRemote:"$REMOTEMD5
fi

This returns line 4: [6135222a12f06b2dfce6a5c1b736891e: command not found

I've tried using ' or " around the $LOCALMD5 but never seem able to get this to compare the outputs. What am I doing wrong? Thanks

Joachim Isaksson · Accepted Answer · 2012-01-09 19:06:44Z

26

Try;

if [ "$LOCALMD5" == "$REMOTEMD5" ]

which should work better.

Edit: I think you got == and != reversed in your code.

edited Jan 9, 2012 at 19:06

answered Jan 9, 2012 at 18:55

Joachim Isaksson

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6 Comments

moztech Over a year ago

Thanks for trying however this still returns command not found

Joachim Isaksson Over a year ago

Strange, works fine for me when I run it. What is the specific error message now?

moztech Over a year ago

Well spotted, I've tried this so many ways around today my eyes were telling me lies. Now works correctly

jaypal singh Over a year ago

@moztech Also, try to use [[ instead of [. Read this .. it's good stuff :)

svandragt Over a year ago

You MUST have spaces after [ and before ]. The hint is in the error message which starts with [

|

Mithrandir · Accepted Answer · 2015-01-19 12:49:31Z

10

I think it should be like this:

#!/bin/sh
REMOTEMD5=$(ssh user@host 'md5sum file.txt')
LOCALMD5=$(md5sum 'file.txt')
if [ "$LOCALMD5" == "$REMOTEMD5" ]
then
  echo "all OK"
else
  echo -e "no match, Local:"$LOCALMD5"\nRemote:"$REMOTEMD5
fi

The space between the bracket and the value is important!

edited Jan 19, 2015 at 12:49

answered Jan 9, 2012 at 18:55

Mithrandir

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4 Comments

moztech Over a year ago

Very close, I'm now getting no match, Local: 6135222a12f06b2dfce6a5c1b736891e file.txt Remote: 6135222a12f06b2dfce6a5c1b736891e file.txt

Mithrandir Over a year ago

The values are identical -> your condition says if the values are unequal the script should print ok ...., seems fine to me!

moztech Over a year ago

Thanks, as noted by @JoachimIsaksson I had got my logic reversed from an earlier attempt as well as some bad code

IQAndreas Over a year ago

As already mentioned in the comments, that != needs to be ==. I'd edit the answer myself, but StackOverflow requires me to make at least 6 characters worth of changes.

IQAndreas · Accepted Answer · 2015-01-19 12:57:07Z

7

[ isn't bash syntax, it is a command. So you must have a space between it and its first argument $LOCALMD5. There also needs to be a space between $REMOTEMD5 and ].

edited Jan 19, 2015 at 12:57

IQAndreas

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answered Jan 9, 2012 at 18:56

Kyle Jones

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