Concatenating strings fails when read from certain files

Question

I have a web application that is deployed to a server. I am trying to create a script that amoing other things reads the current version of the web application from a properties file that is deployed along with the application.

The file looks like this:

//other content
version=[version number]
build=[buildnumber]
//other content

I want to create a variable that looks like this: version-buildnumber

Here is my script for it:

VERSION_FILE=myfile

VERSION_LINE="$(grep "version=" $VERSION_FILE)"
VERSION=${VERSION_LINE#$"version="}
BUILDNUMBER_LINE=$(grep "build=" $VERSION_FILE)
BUILDNUMBER=${BUILDNUMBER_LINE#$"build="}
THEVERSION=${VERSION}-${BUILDNUMBER}

The strange thing is that this works in some cases but not in others. The problem I get is when I am trying to concatenate the strings (i.e. the last line above). In some cases it works perfectly, but in others characters from one string replace the characters from the other instead of being placed afterwards.

It does not work in these cases:

When I read from the deployed file
If I copy the deployed file to another location and read from there

It does work in these cases:

If I write a file from scratch and read from that one.
If I create my own file and then copy the content from the deployed file into my created file.

I find this very strange. Is there someone out there recognizing this?

Looks like you have some stray $ in there -- VERSION=${VERSION_LINE#version=} — glenn jackman
– glenn jackman, Commented May 7, 2012 at 13:49
@LudwigMagnusson, either convert the CRNL files with dos2unix, or filter out the CR with sed 's/\r$//' — glenn jackman
– glenn jackman, Commented May 7, 2012 at 13:51
@nsfyn55: stackoverflow.com/search?q=user%3A26428+pure+%5Bbash%5D — Dennis Williamson
– Dennis Williamson, Commented May 7, 2012 at 14:36

Dennis Williamson · Accepted Answer · 2012-05-07 13:57:55Z

1

It is likely that your files have carriage returns in them. You can fix that by running dos2unix on the file.

You may also be able to do it on the fly on the strings you're retrieving.

Here are a couple of ways:

Do it with sed instead of grep:

VERSION_LINE="$(sed -n "/version=/{s///;s/\r//g;p}" $VERSION_FILE)"

and you won't need the Bash parameter expansion to strip the "version=".

OR

Do the grep as you have it now and do a second parameter expansion to strip the carriage return.

VERSION=${VERSION_LINE#$"version="}
VERSION=${VERSION//$'\r'}

By the way, I recommend habitually using lowercase or mixed case variable names in order to reduce the chance of name collisions.

answered May 7, 2012 at 13:57

Dennis Williamson

364k95 gold badges386 silver badges446 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Giacomo · Accepted Answer · 2012-05-07 12:34:22Z

1

Given this foo.txt:

//other content
version=[version number]
build=[buildnumber]
//other content

you can extract a version-build string more easily with awk:

awk -F'=' '$1 == "version" { version = $2}; $1 == "build" { build = $2}; END { print version"-"build}' foo.txt

I don't know why your script doesn't work. Can you provide an example of erroneous output?

From this sentence:

In some cases it works perfectly, but in others characters from one string replace the characters from the other instead of being placed afterwards.

I can't understand what's actually going on (I'm not a native English speaker so it's probably my fault).

Cheers, Giacomo

answered May 7, 2012 at 12:34

Giacomo

11.3k5 gold badges27 silver badges25 bronze badges

1 Comment

Ludwig Magnusson Over a year ago

With your code, the behaviour is acctually still the same. Let me explain the error more in detail with this example: version=3.2.1 build=87 excpected output: 3.2.1-87 Actual output -87.1 It is as if the second string (-87) is placed "on top of" the beginning of the first sting, i.e the first 3 letters are replaced by the second string.

Collectives™ on Stack Overflow

Concatenating strings fails when read from certain files

2 Answers 2

Comments

1 Comment

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Linked

Related