Небольшой скрипт

df -H | grep -vE '^Filesystem|tmpfs|cdrom' | awk '{ print $5 " " $1 }' | while read output;
do
  echo $output
  usep=$(echo $output | awk '{ print $1}' | cut -d'%' -f1  )
  partition=$(echo $output | awk '{ print $2 }' )
  if [ $usep -ge 90 ]; then
echo "Running out of space \"$partition ($usep%)\" on $(hostname) as on $(date)" |
     mail -s "Alert: Almost out of disk space $usep%" 
fi
done

# ls -l /usr/sbin/fs_check.csh
-rwxr-xr-x   1 root     system       873 Jun  3  2007 /usr/sbin/fs_check.csh

# cat /usr/sbin/fs_check.csh

#! /bin/csh

# find fs which are more than 90% filled
set d = ( `df -k | awk '$5~/%/ && $6!~/proc/ {split($5,a,"%"); if(a[1]>90) print $6"-"$5}'` )

set qq='"'
set pdf = 0
#send message to OVO (hp1) for each overfulled fs.
foreach i ($d)
        set fs = `echo $i | cut -d'-' -f1`
        set df = `echo $i | cut -d'-' -f2`
        # check a flag (don't send identical messages)
        if ( -e $fs/.opcmsg_fs ) source $fs/.opcmsg_fs
        set ndf = `echo $df | cut -d'%' -f1`
        if ($ndf > $pdf) then
                echo "set pdf = $ndf" > $fs/.opcmsg_fs
                # send mail here instead of rsh
                rsh -l axp3031 hp1 "/opt/OV/bin/OpC/opcmsg a=df o=fs msg_grp=OS msg_t=${qq}$fs is $df threshold is 90%${qq} node=axp30 severity=critical"
        endif
end

# remove flag for all FS which used less than threshold.
df -k | awk '$5~/%/ && $6!~/proc/ {split($5,a,"%"); if(a[1]<85) print $6"/.opcmsg_fs"}' | xargs rm -f

#!/bin/bash

DAT=/mnt/data
FDAT=$(df -B M | grep $DAT | awk '{print $4}' | sed 's/M//')

if [ $FDAT -le 2000 ]; then
   echo 'места нет, осталось '$FDAT'Mb'
fi;

$ echo -n awk -v re="$DAT" '$0 ~ re { gsub("M",""); print $4}' |wc -c
48
$ echo -n awk '/'$DAT'/ { gsub("M",""); print $4}' |wc -c
36