Strange behavior in shell script variables

Question

I writing a shell script to parse some file using grep and use the result in subsequent commands.

The relevant part of the source code is

VERSION=`grep "^Stable tag:" readme.md | awk -F' ' '{print $NF}'`
echo $VERSION
echo "Readme file version is $VERSION is it correct"

The relevant line in the readme.md file is

Stable tag: 2.2.2

You would expect a output of

2.2.2
Readme file version is 2.2.2 is it correct

But I am getting the following as the output

2.2.2
 is it correctrsion is 2.2.2

I am pretty sure there is no (non-printable or non-ascii) character at the end of line in my text file. I checked it by enabling the :set invlist command in vim.

Any idea why it is happening like this? Or any other ideas to debug this issue?

You can use awk alone without grep: awk -F' ' '/^Stable tag:/{print $NF}' readme.md — aragaer
– aragaer, Commented Dec 21, 2012 at 13:40
@aragaer Thanks. Didn't know that I can use awk this way. Now that I have to include tr also (see the answer below), do you think I can still do it using awk alone? — Sudar
– Sudar, Commented Dec 21, 2012 at 13:56
man awk and I see sub there. Probablly something like awk -F' ' '/^Stable tag:/{sub("\r", "", $NF); print $NF}' readme.md, though I'd think about sed at that point already. — aragaer
– aragaer, Commented Dec 21, 2012 at 15:57

kmkaplan · Accepted Answer · 2012-12-21 13:43:53Z

2

This looks like a DOS edited file and you working on a Unix like system. Strip the carriage return (Ctrl-M).

You could use tr(1) to remove those:

VERSION=`grep "^Stable tag:" readme.md | tr -d '\015' | awk -F' ' '{print $NF}'`

Awk probably also has some builtin feature to work on these but I do not know awk enough for this.

edited Dec 21, 2012 at 13:43

answered Dec 21, 2012 at 13:38

kmkaplan

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6 Comments

Sudar Over a year ago

Any idea how I can remove it from the shell script variable?

glenn jackman Over a year ago

tr -d '\r' also works, and is possibly more understandable than an octal code.

glenn jackman Over a year ago

Use VERSION=$(sed '/Stable tag:/s/.* $.*$\r/\1/' readme.md) instead of the grep|tr|awk pipeline

aragaer Over a year ago

VERSION=$(sed -n '/Stable tag:/s/.* $.*$\r/\1/p' readme.md) as readme.md might contain other lines too.

kmkaplan Over a year ago

@glennjackman & aragaer: these should be answers, not comments.

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