mac homebrew python3 devel install prioritization & link checks

python3-link.sh

#!/usr/bin/env bash
# When "brew upgrade python3 --devel", make the devel version
#  the default python3 version, along w/ other py3-tools
# brew python 3.5 --devel installs seem to consistently mislink.
#  this tries to correct.

# first, make any python3 apps in bin point to the python3-devel version
# next, make any current release python apps link to version-specific
#  names,  e.g. python3 => python3.5, but python3.4 => python3.4
BN='/usr/local/bin'
PY='/usr/local/Cellar/python3'

DEBUG() {
    # pick one of the following lines
    :
    # echo "$*"
}
## pass these into the script to modify defaults
# the release py3 version
REL="${REL:-3.4.3}"
#default to last created directory
DEV="${DEV:-$(ls -rt ${PY} | tail -1)}"

# 1) check for scripts which don't link to the DEV version
scr=()  # collect DEV scripts
for i in $PY/$DEV/bin/*; do
    scr+=(${i/*\//});
done
# cd, so we can pass the array to ls; 9th field (i) is target filename
(cd $BN; ls -l ${scr[@]}) |
 grep -v $DEV | while read a a a a a a a a i a; do  # a is discarded;
    # assuming everything in bin space is a symlink
    if [ -L $BN/$i ]; then
        ln -s -f $PY/$DEV/bin/$i $BN/$i
    else  # for now, just report it...
        echo ">>> NOT PROCESSESED:  $BN/$i"
    fi
done
# 2) for BN located scripts, check the shell executor (if DEV)
#  none for now, but check anyway:
### >>> done in the if...else..., above
#
# 3) for DEV scripts, check the target shell executor (redirect w/ brew)
# sort thru the scripts, and find the uniq references -
#   most likely they will point to a single 'opt' instance, which may
#   need updating;
shell_runner() {
    if file -b $1 | fgrep 'script text'>/dev/null; then
        # filter those paths which don't match our DEV version
        head -1 $1 | grep -v $DEV
    fi
}
# list of target scripts;
#   these point somewhere other than DEV in Cellar
trg=()
for i in $PY/$DEV/bin/*; do
    # these will most likely link into Cellar/.../Frameworks scripts:
    #  if it's not a script, don't process
    n=$(shell_runner $i)
    DEBUG "  >> n: [$n] ${#n}"
    [ -z "$n" ] || trg+=(/${n#*/})
done #  | sort -u | cut -c 3-))
DEBUG "...trg: [${trg[@]}]"
# next, make sure these are run by the correct DEV version
for i in $(echo ${trg[@]} | tr ' ' '\n'| sort -u); do
    # collected the linked-to shell executor, e.g. #!/bin/foo
    #  now find the links
    unset n
    # 9th item of (ls -l) is our link to replace
    DEBUG "i: $i"
    read a a a a a a a a n a < <(
        ls -l /${i} | grep -v $DEV
    )
    DEBUG "... n: [${n}] (${#n})"
    if [ -n "$n" ]; then
        # pick same target as Cellar space has for this cmd:
        #  e.g. ${n##*/} == python3.5
        dest=$(ls -l $PY/$DEV/bin/${n##*/})
        # link, e.g., python3.5 to same destination as DEV's link
        DEBUG " ..." ln -s -f "${dest/* /}" $n
        ln -s -f "${dest/* /}" $n
    fi
done

### finally, verify all REL scripts are properly linked
scr=()
# release version is just the major.minor part of REL:
for i in $PY/$REL/bin/*${REL%.*}; do
    scr+=(${i##*/})
done
echo "Verifying $REL is appropriately linked:"
(cd $BN; ls -l ${scr[@]}) | grep -v $REL
echo "...if any links were shown above, these need fixing."
echo "DONE"