04_04_undoing.txt

#========================================================================
#    EPISODE - UNDOING CHANGES
#    SECTION - UNDO CHANGES ASSOCIATED WITH A COMMIT (REVERT)
#========================================================================

# UNDO CHANGES ASSOCIATED WITH A COMMIT (revert)

# git revert removes the changes applied in a specified commit. 
# However, rather than deleting the commit from history, git works out 
# how to undo those changes introduced by the commit, and 
# appends a new commit with the resulting content.

# Let’s try it on our example. 
# Modify the paper, describing the SMPS which is another instrument used 
# to measure particle sizes, and then make a commit.

# ** FILE EDITS **
#
# Modify introduction in paper.md:
#
# # Introduction
# We present aircraft measurements of BBOA over West Africa.Particle size was 
# measured using a PCASP, (Bloggs et al 2004) and SMPS instrument
# Jones (1998) conducted several studies in the region, but continental scale
# measurements have not been made.
# 
# A large uncertainty in BBOA modelling is the extent to which values in the
# literature can be applied at a local scale.
# 

git add paper.md
git commit -m "Describe SMPS"

# We now realise that what we’ve just done in our journal article is incorrect 
# because we are not using the data from that instrument. 
# Some of the data got corrupted, and due to problems with the logging computer 
# we are not going to use that data. So it makes sense to abandon the commit completely.

# Let's undo changes introduced by most recent commit

git revert HEAD		

# When we revert, a new commit is created.
# - END -