snp: Wrap shell command in BTRFS snapper pre-post snapshots and log outputs.

snp

#!/usr/bin/env bash
# Runs a command wrapped in btrfs snapper pre-post snapshots.
# Usage: $ snp <commands>
# e.g.: $ snp pacman -Syyu
# Requirements: snapper (https://wiki.archlinux.org/title/snapper)
# The latest version of this script is hosted at https://gist.github.com/erikw/5229436

log_path="/var/local/log/snp"
date=$(date "+%Y-%m-%d-%H%M%S")
log_file="${log_path}/snp_${date}.log"

! [ -d $log_path ] && mkdir -p $log_path
# Log stdout and stderr. Reference: http://stackoverflow.com/questions/3173131/redirect-copy-of-stdout-to-log-file-from-within-bash-script-itself
exec >  >(tee -a "$log_file")
exec 2> >(tee -a "$log_file" >&2)

cmd="$@"

echo "> Logging to: ${log_file}"

snapshot_nbr=$(snapper create --type=pre --cleanup-algorithm=number --print-number --description="${cmd}")
echo "> New pre snapshot with number ${snapshot_nbr}."
echo -e "> Running command \"${cmd}\".\n"

eval "$cmd"

snapshot_nbr=$(snapper create --type=post --cleanup-algorithm=number --print-number --pre-number="$snapshot_nbr")
echo -e "\n> New post snapshot with number ${snapshot_nbr}."




# Snapper has a --command option nowadays. But it works worse, the output from the command is not printed separately from the snaptshot number, just becomes a mess.
#echo "> Running command \"${cmd}\"."
#snapshot_nbr=$(snapper create --command "${cmd}" --print-number --cleanup-algorithm=number --description="${cmd}" | tail -1)
#echo -e "\n> New pre-post snapshot with numbers ${snapshot_nbr}."

Hi! Out of curiosity, why did you choose /var/local/log instead /var/log?

Hi msx!

I use the local directory to not confuse my custom files and scripts with the systems. The very same reason people put their own system scripts under /usr/local/{bin,sbin} instead of /usr/{bin,sbin} :)

Just passing by to say TY and let you know that I'm using snp all the time for all sort of things. Cheers!

ZFS users!

Check out znp

=)

Hi,
May I submit a PKGBUILD for this script to the AUR? I believe it will help out a lot of people.

@Fire100265 Hey, you're very welcome to make a PKGBUILD for this! I too find this little utility immensely useful for many semi- to dangerous Linux operational tasks.

I don't know how well PKGBUILDs work with gists. If it's not working out well, I can move this script to a proper Github git repo. Let me know if the Gist works first though

@erikw Thank you! I have written a PKGBUILD and I will be submitting it to the AUR soon. As you have predicted, gists do not work very well with PKGBUILDs. Due to this, I copied all the text into a file and used it as the source.
Edit: Here is the link to the AUR page. Please let me know of any changes I should make. I can add you as a maintainer if you wish.

@Fire100265 The PKGBUILD looks great!

There can only be 1 maintainer in AUR right? To distribute comments and future maintenance questions you could tell people to reach out to me as well of your unavailable, here at Github or my AUR profile https://aur.archlinux.org/account/erikw :)

Thank you for your reply! I added you as a maintainer. Please let me know if you can access the package.
Edit: please edit the PKGBUILD to add your email.

✅