Possible to run multiline shell command/string in groovy/gradle? - jenkins

Question

In gradle 7 I have created this method:
def shellCmd(String cmd) {
exec {
executable "sh"
args "-c", cmd
}
}
And this "pure" groovy version:
def shellCmd2(String cmd) {
def process = cmd.execute()
def output = new StringWriter(), error = new StringWriter()
process.waitForProcessOutput(output, error)
}
Which I call from another method e.g.:
def myMethod() {
shellCmd('ls -la')
}
I am now experimenting with getting it to work with multi-line (jenkins like) shell commands:
def myMethod() {
def cmd = """
for i in \$(ls -la); do
if [[ \$i == 'settings.gradle' ]]; then
echo "Found $i"
fi
done
"""
shellCmd(cmd)
}
but it fails with:
script '/home/user/samples/build.gradle': 47: Unexpected input: 'i' # line 47, column 5.
for i in $(ls -la); do
^
1 error
Probably I am breaking all the rules here but any input?
Also tried most of the suggestions here:
What's wrong with Groovy multi-line String?
but no luck so far.
Also based on the suggestion below I have tried to use shellCmd2 method (I am leaning towards using a plain groovy method for this to make it easier to debug outside of gradle) with:
def myMethod() {
def cmd = """
for i in \$(ls -la); do
if [ \$i = 'settings.gradle' ]; then
echo "Found \$i"
fi
done
"""
shellCmd2(cmd)
}
But that gives:
Caught: java.io.IOException: Cannot run program "for": error=2, No such file or directory
java.io.IOException: Cannot run program "for": error=2, No such file or directory
So seems the for keyword is now causing an issue.

Answer 1

There is nothing wrong with your multiline string. I had to change three things to make your code work:
Use single brackets [ and ]
Use single equal sign (=)
Escape the missing $i variable which was being interpreted as a Groovy variable.
You are using sh so you should only use POSIX compatible features.
Code:
def shellCmd(String cmd) {
exec {
executable "sh" // or use another shell like bash or zsh (less portable)
args "-c", cmd
}
}
def myMethod() {
def cmd = """
for i in \$(ls -la); do
if [ \$i = 'settings.gradle' ]; then
echo "Found \$i"
fi
done
"""
shellCmd(cmd)
}
You can compare with double brackets with shells like zsh and bash.