Jenkinsfile idiosynchrasies with escaping and quotes

Jenkinsfile.groovy

node {
    echo 'No quotes in single backticks'
    sh 'echo $BUILD_NUMBER'
    echo 'Double quotes are silently dropped'
    sh 'echo "$BUILD_NUMBER"'
    echo 'Even escaped with a single backslash they are dropped'
    sh 'echo \"$BUILD_NUMBER\"'
    echo 'Using two backslashes, the quotes are preserved'
    sh 'echo \\"$BUILD_NUMBER\\"'
    echo 'Using three backslashes still results in preserving the single quotes'
    sh 'echo \\\"$BUILD_NUMBER\\\"'
    echo 'To end up with \" use \\\\\\\" (yes, seven backticks)'
    sh 'echo \\\\\\"$BUILD_NUMBER\\\\\\"'
    echo 'This is fine and all, but we cannot substitute Jenkins variables in single quote strings'
    def foo = 'bar'
    sh 'echo "${foo}"'
    echo 'This does not interpolate the string but instead tries to look up "foo" on the command line, so use double quotes'
    sh "echo \"${foo}\""
    echo 'Great, more escaping is needed now. How about just concatenate the strings? Well that gets kind of ugly'
    sh 'echo \\\\\\"' + foo + '\\\\\\"'
    echo 'We still needed all of that escaping and mixing concatenation is hideous!'
    echo 'There must be a better way, enter dollar slashy strings (actual term)'
    def command = $/echo \\\"${foo}\\\"/$
    sh command
    echo 'String interpolation works out of the box as well as environment variables, escaped with double dollars'
    def vash = $/echo \\\"$$BUILD_NUMBER\\\" ${foo}/$
    sh vash
    echo 'It still requires escaping the escape but that is just bash being bash at that point'
    echo 'Slashy strings are the closest to raw shell input with Jenkins, although the non dollar variant seems to give an error but the dollar slash works fine'
}

for build number you could also just do this i believe? ${env.BUILD_NUMBER}

I think "idiosynchrasies" is being overly polite!

thanks, you saved my day

@nowayride I was struggling with interpolation in multiline strings this morning...

FWIW, my issue was that interpolation is NOT supported in single and triple single quoted strings: http://docs.groovy-lang.org/latest/html/documentation/#_string_interpolation

so interpolating in ''' did not work, whereas interpolating in """ worked just fine.

Hi I'm having some issues trying to do this :
sh """ sed -i -e 's/%1//g' \${variable}/foo.txt """
Looks like the "%" is getting some issues in the jenkins file, any idea? also I tried with $1 but it is not working

Thank you for compiling this. Have been fighting some Jenkinsfile string handling oddities, and this helped me nail them down. dollar slashy strings are turning out to be my bestest friend.

Man.. what a mess this is! Eventually when you get it working, its an eye sore in the code.

Thank you for putting this list together.. spent most of the day trying to figure out a simple sh command with a sed replacement ..

I believe Jenkins needs an args: parameter for the "sh" pipeline command, right now we have script:, returnStdout: and returnStatus: both useful to avoid messing with the filesystem. However, is clearly impossible or at least difficult to have clean (and secure) executions, with "sh", just my 2c, maybe Jenkins should do this automatically, but I'm not sure if I want that kind of magic, I rather depend on args.

Like:

sh(script: "echo", args: ["hello", "world", env.MY_ENV, my_other_def])

or a new pipeline command to avoid overloading "sh"

sh(script: "echo", args: ["hello", "world", env.MY_ENV, my_other_def])

On both cases echo the program, not the shell built-in should be executed, Jenkins should look for the program on the systems $PATH/%PATH% but also an absolute path should be supported, like a regular groovy execute on a List.

["/bin/echo", "foo", "bar"].execute()

Is not common to have groovy's execute() allowed on Jenkins sandboxed environment, maybe for good reasons...

I've converted the last comment into a Jenkins issue, let's see what happens. https://issues.jenkins-ci.org/browse/JENKINS-44231

Thank you for making this! To help others in the future, here's how you would do a pipe into sed. Don't need to add extra escapes:

    def imageTag = 'feature/someBranchName'
    def command = $/echo ${imageTag} | sed 's/\//\-/'/$
    
    imageTag = sh(returnStdout: true, script: command).trim()
    sh("echo ${imageTag}")
    // outputs feature-someBranchName