Check file lifetime stats on a GPFS

gpfs_expiration_checker.sh

# I usually put this in my ~/.bash_aliases
# A portion of our GPFS storage removes files after 21 days of creation.
# `stat` does not show creation time, so we have to resort to parsing the
# output of `mmlsattr`

ftime() {
    # Usage: 
    #   ftime path/to/file
    # 
    # Outputs:
    #   File [path/to/file] has lived for 18:04:52.
    #   File [path/to/file] has roughly 3 days left alive.
    #   File [path/to/file] will die on 2019/01/25 @ 11:30.
    #   
    # Notes:
    # may or may not work with directories, e.g. `ftime path/to/directories`
    # will not work with globs, e.g. `ftime path/to/*`
    
    if [[ $# -ne 1 ]]; then
        >&2 echo "Specify a file!"
        exit 1
    fi
    if [[ "$(readlink -f ${1} | cut -d/ -f2)" != "gpfs" ]]; then
        >&2 echo "File [${1}] must be on /fastscratch/"
        exit 1
    fi
    
    mmlsattr=/usr/lpp/mmfs/bin/mmlsattr
    birth_time=$(mmlsattr -L $1 | grep creat | cut -d: -f2-)
    birthday=$(date -d "${birth_time}" '+%s')
    now=$(date '+%s')
    
    expiredays=21
    datediff=$((now-birthday))
    daysalive=$((datediff/86400))
    daysleft=$((expiredays - daysalive))
    deathday=$(date -d@"$((birthday+expiredays*86400))" '+%Y/%m/%d @ %H:%M')
    
    echo "File [$1] has lived for ${daysalive}:$(date -u -d@${datediff} +%H:%M)."
    echo "File [$1] has roughly ${daysleft} days left alive."
    echo "File [$1] will die on ${deathday}."
}