Bash Script - Check mounted devices - linux

Question

What I'm trying to do -
In the end, I want a script that checks for 3 devices, an SD card, Backup1 & Backup2. They've all been set to auto-mount at their respective mountpoints. The script should check for SD card first, if this fails, then a warning should be sent, and nothing more. If SD is okay, but only one backup is mounted, then ask for confirmation to go ahead with rsync to mounted backup. If all devices are mounted, then rsync from SD card to both backups.
Currently I'm just trying to get the device check nailed, using echo commands. Here's what I have (after multiple attempts) -
if ! mount | grep /media/card >/dev/null
then
echo "ERROR: SD card not mounted, aborting"
else
if ! mount | grep /media/backup >/dev/null
then
if ! mount | grep /media/backup2 >/dev/null
then
echo "ERROR: No backup devices"
else
echo "CAUTION: Backup_2 missing, Backup_1 OKAY"
fi
else
if ! mount | grep /media/backup2 /dev/null
then
echo "CAUTION: Backup_1 missing, Backup_2 OKAY"
else
echo "SUCCESS: All devices OKAY"
fi
fi
fi
Which isn't working. I'm getting confused by all the nested 'if's and surely there's a simpler way? Perhaps something that checks each device independently, then returns values that equate to the various combinations (0=no devices, 1=sd only, 2=sd & backup1, 3=sd & backup 2, 4 = all okay) which then is read and decides next part of script to run? If not, where has this way gone wrong?
Any help is appreciated

Answer 1

Use mountpoint, which returns success (0) if the path is a mounted device, and 1 otherwise:
#!/bin/bash
check_mountpoint(){
if mountpoint -q $1
then
printf "%s\n" "$1 is mounted"
return 0
else
printf "%s\n" "$1 is not mounted"
return 1
fi
}
check_mountpoint /media/sd
if [ $? -gt 0 ]
then
printf "%s\n" "aborting"
exit 0
fi
check_mountpoint /media/backup1
check_mountpoint /media/backup2
this is your code corrected, i hope it will help.
if mountpoint -q /media/sd
then
if mountpoint -q /media/backup
then
if mountpoint -q /media/backup2
then
echo "SUCCESS: All devices OKAY"
# run your command here
else
echo "CAUTION: Backup_2 missing, Backup_1 OKAY, SD OKAY"
# run your command here
fi
else
if mountpoint -q /media/backup2
then
echo "CAUTION: Backup_1 missing, Backup_2 OKAY, SD OKAY"
# run your command here
else
echo "SD OKAY , BACKUP Devices missing"
fi
fi
else
echo "SD is missing , Exit"
fi

Answer 2

Solved! Part of the problem was using mount | grep /media/backup > /dev/null as there's an issue with similar names, so /media/backup2 being mounted meant it was counting both devices as mounted.
Using grep -q /media/backup2\ /proc/mounts works in a similar way, or at least produces the same outcome, just without the naming issue.
I've also changed the way the if statements work, it now checks for SD card, if that fails, then it aborts. It then checks for which devices are mounted with a fairly simple flow.
Here's the code:
GNU nano 2.2.6 File: backupSD2.sh Modified
#!/bin/bash
#Check for SD
if ! grep -q /media/card\ /proc/mounts
then
echo "ERROR: NO SD CARD"
exit 0
else
echo "SD OKAY..."
fi
#Check for Backup Devices
if (( grep -q /media/backup\ /proc/mounts ) && ( grep -q /media/backup2\ /proc/mounts ))
then
echo "Both Backups mounted"
elif grep -q /media/backup\ /proc/mounts
then
echo "CAUTION: Backup_2 missing, Backup_1 OKAY"
elif grep -q /media/backup2\ /proc/mounts
then
echo "CAUTION: Backup_1 missing, Backup_2 OKAY"
else
echo "ERROR: NO BACKUP DEVICES"
exit 0
fi
After the 'echo' commands is where I'll be putting the rsync commands.
The final exit 0 is probably unnecessary, but I don't think it's doing any harm and reassures that it's not going to try any more commands.

Answer 3

Check for 1 required mounted source AND at least 1 required mounted target
The best aproach for this is to build an array of mounted devices, then evaluate de count of elements in array.
Introduction
1. Care! Using grep -q "$dev" /proc/mounts will fail to found spaced mount points!
/media/spaced target
in /proc/mounts will appear as
/media/spaced\040target
command printf -v varname '%b' $varname could help!
2. Using bash array and associative array to avoid fork
Instead of doing many fork to grep, (browsing same file many time), you could use bash for the job.
3. Parallelizing rsync on many targets
Using backgrounded jobs and wait -n -p <VARNAME>, you could do rsync on many targets simultaneously.
4. Using /proc/self/mounts instead of /proc/mounts
After having a look at man 5 proc.
Here is a script, within:
you could configure as many backup targets you want.
if all targets are mounted, script go on
if no targets are mounted, script stop and
if at least one target is mounted but not all, user is asked for continuing.
(this could be avoided by using -y/-n optional flag)
On second part, all rsync are run as background job (parallelized),
then script wait for all rsync to be done,
then print each result code with corresponding target,
before finish
The script:
#!/bin/bash
source='/media/card'
backups=(
/media/backup
/media/backup2
/media/other\ backup
)
die() {
echo "$0[$$] ERROR: $#" >&2
exit 1
}
warn() {
echo "$0[$$] WARNING: $#" >&2
}
declare -A tobemounted="(['$source']='source')"
for target in "${backups[#]}";do
tobemounted["$target"]=backup
done
mountedbk=()
while read -r _ mpnt _;do
printf -v mpnt %b $mpnt
if [[ -v tobemounted["$mpnt"] ]] ;then
[[ ${tobemounted["$mpnt"]} == backup ]] && mountedbk+=("$mpnt")
unset tobemounted["$mpnt"]
fi
done </proc/self/mounts
[[ -v tobemounted["$source"] ]] && die "Source '$source' not mounted."
for missing in "${!tobemounted[#]}";do
warn "Backup '$missing' not mounted."
done
(( ${#mountedbk[#]} == 0 )) && die "No backup present."
if (( ${#mountedbk[#]} < ${#backups[#]} ));then
printf -v msg 'Only %d / %d backups targets are present.' \
${#mountedbk[#]} ${#backups[#]}
warn "$msg"
case $* in
*-n* ) die Exit now. ;;
*-y* ) warn Process anyway. ;;
* ) read -rsn 1 -p 'Process anyway? (N/y): ' ans
[[ "${ans//[yY]}" ]] && { echo No; die 'User abort.';}
echo Yes ;;
esac
fi
pids=() resultmsg=(success)
for target in "${mountedbk[#]}";do
echo rsync "$source/." "$target/." &
pids[$!]="$target"
done
while ((${#pids[#]}));do
wait -np pid
printf 'backup to "%s" end with %s.\n' \
"${pids[pid]}" "${resultmsg[$?]:-error}"
unset 'pids[pid]'
done
Replace line:
echo rsync "$source/." "$target/." &
by somethine like:
rsync <your rsync options> "$source/SourcePath/." "$target/TargetPath/." &
Outputs could look like:
When source not ready:
$ ./backups.sh
./backups.sh[3721068] ERROR: Source '/media/card' not mounted.
When none of the targets are ready.
$ ./backups.sh
./backups.sh[3729071] WARNING: Backup '/media/backup' not mounted.
./backups.sh[3729071] WARNING: Backup '/media/backup2' not mounted.
./backups.sh[3729071] WARNING: Backup '/media/other backup' not mounted.
./backups.sh[3729071] ERROR: No backup present.
When some but not all targets are ready.
$ ./backups.sh
./backups.sh[3725569] WARNING: Backup '/media/backup2' not mounted.
./backups.sh[3725569] WARNING: Backup '/media/other backup' not mounted.
./backups.sh[3725569] WARNING: Only 1 / 3 backups targets are present.
Process anyway? (N/y): Yes
backup to "/media/backup" end with success.
$ ./backups.sh
./backups.sh[3729355] WARNING: Backup '/media/backup' not mounted.
./backups.sh[3729355] WARNING: Backup '/media/other backup' not mounted.
./backups.sh[3729355] WARNING: Only 1 / 3 backups targets are present.
Process anyway? (N/y): Yes
backup to "/media/backup2" end with success.
$ ./backups.sh
./backups.sh[3854708] WARNING: Backup '/media/backup2' not mounted.
./backups.sh[3854708] WARNING: Backup '/media/other backup' not mounted.
./backups.sh[3854708] WARNING: Only 1 / 3 backups targets are present.
Process anyway? (N/y): No
./backups.sh[3854708] ERROR: User abort.
$ ./backups.sh -y
./backups.sh[3734321] WARNING: Backup '/media/backup' not mounted.
./backups.sh[3734321] WARNING: Backup '/media/other backup' not mounted.
./backups.sh[3734321] WARNING: Only 1 / 3 backups targets are present.
./backups.sh[3734321] Process anyway.
backup to "/media/backup2" end with success.
$ ./backups.sh -n
./backups.sh[3854855] WARNING: Backup '/media/backup2' not mounted.
./backups.sh[3854855] WARNING: Backup '/media/other backup' not mounted.
./backups.sh[3854855] WARNING: Only 1 / 3 backups targets are present.
./backups.sh[3854855] ERROR: Exit now.
When all targets are ready.
$ ./backups.sh
backup to "/media/backup" end with success.
backup to "/media/backup2" end with success.
backup to "/media/other\ backup" end with success.