On 2012-12-17 11:53, Russell Coker wrote:

http://etbe.coker.com.au/2012/12/17/using-btrfs/

I've written my own scripts to manage snapshot backups on BTRFS and published them at the above URL.

Hi Russell, Reading your scripts, I noticed a few of coding practices that I thought worth commenting on: I'd write it like this, using 'while read' and quoting "$n" just in case. I realise these may not cause *you* grief, but giving you're posting these scripts, I think they should be a little more robust: | #!/bin/bash | # Re the for loop, don't do that [1] | while read -r n | echo "$n" | ssh "$n" "btrfs scrub start -B -d /" | done < <(xm list|cut -f1 -d\ |egrep -v ^Name\|^Domain-0) btrfs-make-snapshot (untested, but should work, and hopefully you get my intent): | #!/bin/bash | set -e | | # usage: | # btrfs-make-snapshot [-d] minutes|days paths | # example: | # btrfs-make-snapshot minutes /home /mail | | btrfs() | { | if (( debug == 1 )) | then | echo btrfs "$@" | else | command btrfs "$@" | fi | } | | # Using capitalised variable names make them look like environment | # variables and may cause clashes if you're not careful. "/msg greybot | # !varcaps" for more info | # Also http://mywiki.wooledge.org/BashFAQ/050 re: storing commands in | # variables. | if [ "$1" == "-d" ]; then | debug=1 | shift | fi | | if [ "$1" == "minutes" ]; then | date=$(date +%Y-%m-%d:%H:%M) | else | date=$(date +%Y-%m-%d) | fi | shift | | # $* is unsafe. "$@" is almost always what you want.[2] | for n in "$@" ; do | btrfs subvol snapshot -r "$n" "$n/backup/$date" | done btrfs-remove-snapshots (same deal as above): | #!/bin/bash | set -e | | # usage: | # btrfs-remove-snapshots [-d] MINSNAPS DAYSNAPS paths | # example: | # btrfs-remove-snapshots 100 100 /home /mail | | btrfs() | { | if (( debug == 1 )) | then | echo btrfs "$@" | else | command btrfs "$@" | fi | } | | if [ "$1" == "-d" ]; then | debug=1 | shift | fi | | minSnaps=$1 | shift | # FIXME: Russell, you never use daySnaps. Is that a bug? Should it be | # in the second loop below? I don't use btrfs so am not sure. | daySnaps=$1 | shift | | for dir in "$@" ; do | base=$(echo "$dir" | cut -c 2-200) | while read -r n | btrfs subvol delete /"$n" | done < <(btrfs subvol list "$dir"|grep "$base"/backup/.*:|head -n -"$minSnaps"|sed -e "s/^.* //") | while read -r n | btrfs subvol delete /"$n" | done < <(btrfs subvol list "$dir"|grep "$base"/backup/|grep -v :|head -n -"$minSnaps"|sed -e "s/^.* //") | done That's more than enough ranting and preaching out of me; hope I'm more enlightening than annoying. 1. 2012-12-17_12:00:11 -!- Irssi: Starting query in Freenode with greybot 2012-12-17_12:00:19 <mattcen> !for$( 2012-12-17_12:00:20 <greybot> Never do this: for x in $(command) or `command` or $var. for-in is used for iterating arguments, not (output) strings. Instead, use arrays or a while-read loop. See http://mywiki.wooledge.org/BashSheet#Arrays http://mywiki.wooledge.org/DontReadLinesWithFor http://mywiki.wooledge.org/BashFAQ/001 2. 2012-12-17_12:18:38 <mattcen> !$* 2012-12-17_12:18:39 <greybot> The difference between $@ and $*: Unquoted (don't do this!), none at all: both equal $1 $2 .... With double quotes, "$@" expands each element as an argument: "$1" "$2" ..., while "$*" expands to all elements merged into one argument: "$1c$2c..." (where c is the first character of IFS). You almost always want "$@". The same goes for arrays: "${myarray[@]}" -- Regards, Matthew Cengia