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Andrew Kim
Andrew Kim

Reputation: 3335

bash maintain old value for variable

I have this bash script that I want to duplicate a branch and make a PR to a remote repo using that duplicate branch then delete the duplicate branch:

gPullRequest () {
  branch=$(git rev-parse --abbrev-ref HEAD)
  if [ $# -eq 0 ]
    then
      git checkout -b development-$branch
  elif [ $# -eq 1 ]
    then
      git checkout -b release-$branch
  fi
  gp
  prBranch=$(git rev-parse --abbrev-ref HEAD)
  if [ $# -eq 0 ]
    then
      hub pull-request -h org:$prBranch -b org:development
  elif [ $# -eq 1 ]
    then
      hub pull-request -h org:$prBranch -b org:$1
  fi
  git checkout $branch
  git branch -D $prBranch
}

The problem is the variable branch gets re evaluated to what prBranch is pointing to by the time 

git checkout $branch

When this code runs, the branch variable is the new branches name instead of the first value from the first line of code.

Any thoughts on how to preserve the value of branch for later execution of the bash script?

edit

gp () {
  branch=$(git rev-parse --abbrev-ref HEAD)
  git push origin $branch
}

this was previously not present in the original prompt, but is the reason for the bug.

Upvotes: 0

Views: 433

Answers (1)

Charles Duffy
Charles Duffy

Reputation: 295629

This quite certainly means your bp function starts like:

bp() {
  branch=$1
  othervar=$(whatever)
  # ...do stuff here...
}

You can't do that safely, because -- like Javascript -- variables are global by default in bash. Thus, setting branch inside a function you call changes the value in the parent as well.

Always declare your locals, like so:

bp() {
  local branch othervar
  branch=$1
  othervar=$(whatever)
  # ...do stuff here...
}

(Why two separate lines, rather than local branch=$1? Because when you want to move on to local foo=$(bar), the local command eats the exit status of bar, making its success or failure impossible to determine later; maintaining a habit of keeping your local declarations to a separate line avoids the issue).

Upvotes: 1

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