Shell Programming and Scripting

#!/bin/bash
CURRENT=$(df -k /log/logs | grep /log/logs | awk '{ print $5}' | sed 's/%//g')
THRESHOLD=30
if [ "$CURRENT" -gt "$THRESHOLD" ] ; then
echo "Remaining free space is low" > output.txt
else
echo "Space seems ok" > output.txt
fi

+ + df -k /log/logs
+ grep /log/logs
+ awk { print $5}
+ sed s/%//g
CURRENT=
+ THRESHOLD=30
+ [  -gt 30 ]
+ echo Space seems ok
+ 1> output.txt

+ + df -k /log/logs
CURRENT=Filesystem            kbytes    used   avail capacity  Mounted on
/log             20643785 8189598 12247750    41%    /log

+ + grep /log/logs
+ df -k /log/logs
CURRENT=

+ + df -k /log/logs
+ grep /log/logs
+ sed s/%//g
+ awk { print $5}
CURRENT=66
+ THRESHOLD=80
+ [ 66 -gt 80 ]

df -k /log/logs |awk '$1 ~ "^/log"{ print $5+0}'

df -k /log/logs |awk '$1 ~ "^/log"{ print $5+0}'
awk: syntax error near line 1
awk: bailing out near line 1