Issue

I have read a lot about variable expansion in bash scripts this morning but I have still not been able to identify what has caused the script to stop expanding the variable in this line of code:

CURRENT_HASH=`git log --pretty=format:"%H %s" | grep ${LIBRARY_VERSION}-SNAPSHOT | head -1 | cut -d ' ' -f 1`

Here is more context, with comments showing the output of each line:


SCRIPTPATH=`pwd`

# get the application name and library name from the cloned repo in the deploy directory
DEPLOY_DIRECTORY="$(basename `pwd`)"
LIBRARY_SUFFIX="-library.txt"
cd ..
for d in */ ; do
    if [[ "$d" == *"library"* ]] ; then
        LIBRARY_NAME="${d%?}" # myAppLibrary
    fi
    if [[ "$d" != "${DEPLOY_DIRECTORY}" && "$d" != *"library"* ]] ; then
        APP_NAME="${d%?}" # myAppName
    fi
done
    
# get the latest version from the library
cd ..
LIBRARY_LATEST=$(head -n 1 $SCRIPTPATH/../${LIBRARY_NAME}/${APP_NAME}${LIBRARY_SUFFIX})
LIBRARY_VERSION=`echo $LIBRARY_LATEST | sed '$s/,//'`

echo $LIBRARY_LATEST # outputs 320,
echo $LIBRARY_VERSION # outputs 320 (no comma)

# get the hash matching the last frozen version from the app repo
cd $SCRIPTPATH/../$APP_NAME
CURRENT_HASH=`git log --pretty=format:"%H %s" | grep ${LIBRARY_VERSION}-SNAPSHOT | head -1 | cut -d ' ' -f 1`
echo "Current hash: $CURRENT_HASH" # blank

If I do the git log command from the command line I get a hash, as expected.

This block of code was working perfectly last week, but now $CURRENT_HASH is blank every time. If I manually include the ${LIBRARY_VERSION} it works fine. If I manually populate the variable, it works fine. I have also tried $LIBRARY_VERSION to no avail.

Am I missing something obvious? What would cause a variable to stop working?

Solution

As discussed in the comments on the question, the immediate cause of the problem appears to be that the string in $LIBRARY_VERSION has a trailing carriage return character.

A likely underlying cause of the problem is that the file from which the LIBRARY_LATEST variable value was read has recently acquired Windows text file line endings (CRLF).

Unexpected CRLF line endings are a common cause of problems described in questions relating to Bash (and similar shells). These references may be useful:

The first point in the "Before asking about problematic code" section of the Stack Overflow 'bash' Info page
Are shell scripts sensitive to encoding and line endings?
How to convert Windows end of line in Unix end of line (CR/LF to LF)

Answered By - pjh

Answer Checked By - David Marino (WPSolving Volunteer)

Sunday, February 27, 2022

[SOLVED] My bash script suddenly stopped variable expansion in one line of code

Issue

Solution