git-uniqueid

#!/bin/bash
# Author: Gokberk Cinbis, 2017
set -e
#set -o pipefail -e # maybe this instead?

function helpandpanic()
{
    echo 'git-uniqueid <format>'
    echo   
    echo 'Generate a unique experiment id based on date and git hash.'
    echo 'The intended use is to tag the experimental outputs of the current source code.'
    echo
    echo FORMAT OPTIONS
    echo 'date_time_branch_hash_proc (default)'
    echo 'date_time_hash_proc'
    echo
    echo 'GIT HASH STRING'
    echo 'Git directory, no modification: only first few characters of the hash is shown'
    echo 'Git directory, with modified files: <githash>_modified'
    echo 'Not a git directory: "nogit"'
    echo
    echo 'OTHER VARIABLES'
    echo 'branch: The current branch. When in detached-HEAD mode, this is just "HEAD".'
    echo 'proc: hostname.pid, where pid belongs to current script, provided just to reduce the chance of a name conflict'
    echo 
    echo 'EXIT CODES'
    echo '  0 if the git directory is "clean"'
    echo '  1 if the git directory has uncommited changes'
    echo '  2 if not a git repository'
    echo '  3 if arguments are not recognized'
    echo
    echo 'Suggested use of the exit code:'
    echo '  if id=$(git-uniqueid); then'
    echo '      echo run experiment with log id $id'
    echo '  else'
    echo '      echo "there are uncommitted changes or not a git directory"'
    echo '  fi'
    echo
    echo 'PACKAGE'
    echo 'git-uniqueid    Generate a unique log file/directory name for running an experiment'
    echo 'git-writehash   Write git hash into a file'
    echo 'git-checkhash   Check whether the current git hash to make sure the right code-base is being used for evaluating a pre-trained model'
    exit 3
}

if [ "$#" -eq 0 ]; then
    format="date_time_branch_hash_proc"
elif [ "$#" -eq 1 ]; then
    format="$1"
else
    helpandpanic
fi

# date, time, process info
d=`command date +%Y%m%d`
t=`command date +%H.%M.%S` # hour.minute.seconds (dots are useful for time, otherwise very unreadible)
host=`command hostname`
pid="$$"
proc="${host}.${pid}"

# git information
# https://stackoverflow.com/questions/2180270/check-if-current-directory-is-a-git-repository
if git rev-parse --git-dir > /dev/null 2>&1; then
    # https://stackoverflow.com/questions/4120001/what-is-the-git-equivalent-for-revision-number

    # No, this is not reliable and wrong if we're in detached-HEAD state.
    # 'index: commit index relative to the first one, a hacky commit index'
    # commitindex=`git rev-list --full-history --all --abbrev-commit | wc -l | sed -e 's/^ *//'` # commit index

    set +e # forgive errors below
    h=`command git-writehash` # hash
    writehash_exit=$?
    set -e # exit on error

    branch=`command git rev-parse --abbrev-ref HEAD`
    if [[ -z $(command git status -s) ]]; then # see https://stackoverflow.com/questions/3878624/how-do-i-programmatically-determine-if-there-are-uncommited-changes
        rc=$writehash_exit # return code is zero unless git-writehash has reported an error
    else
        # git-writehash does this: h=${h}_modified
        rc=1 # return code
    fi
    # ih="${commitindex}_${h}"
else
    h='notgit' # hash
    branch=''
    ih='notgit' # index_hash
    rc=2 # return code
fi

if [ "$format" == "date_time_branch_hash_proc" ]; then
    branch="${branch}_"
    echo ${d}_${t}_${branch}${h}_${proc}
elif [ "$format" == "date_time_hash_proc" ]; then
    echo ${d}_${t}_${h}_${proc}
#elif [ "$format" == "date_index_hash_time_proc" ]; then
#    echo ${d}_${ih}_${t}.${proc}
else
    echo "UNRECOGNIZED FORMAT"
    helpandpanic
fi

exit $rc