I am learning bash shell and I'm a beginner.
Now, I have a script named for_test
#!/bin/bash
var1=3
until [ $var1 -eq 0 ]
do
echo "Outer loop: $var1"
var2=1
while [ $var2 -lt 5 ]
do
var3=`echo "scale=4; $var1 / $var2" | bc`
echo " Inner loop:$var1 / $var2 = $var3"
var2=$[ $var2 + 1 ]
done
var1=$[ $var1 - 1 ]
done >> temp.log.txt
When I exec it in the terminal, it works well.
Outer loop: 3
Inner loop:3 / 1 = 3.0000
Inner loop:3 / 2 = 1.5000
Inner loop:3 / 3 = 1.0000
Inner loop:3 / 4 = .7500
Outer loop: 2
Inner loop:2 / 1 = 2.0000
Inner loop:2 / 2 = 1.0000
Inner loop:2 / 3 = .6666
Inner loop:2 / 4 = .5000
Outer loop: 1
Inner loop:1 / 1 = 1.0000
Inner loop:1 / 2 = .5000
Inner loop:1 / 3 = .3333
Inner loop:1 / 4 = .2500
But when I exec like this:
at -f for_test 11:10
When the time has come, the script is executed, but I get an infinite loop.
Here's the log.
Outer loop: 3
Inner loop:3 / 1 = 3.0000
Inner loop:3 / 1 = 3.0000
Inner loop:3 / 1 = 3.0000
……
And I found $var2 always equals 1.
What do I do wrong?
My ubuntu version and bash version.
$ uname -a
Linux android_su 2.6.35-32-generic #67-Ubuntu SMP Mon Mar 5 19:39:49 UTC 2012 x86_64 GNU/Linux
$ bash --version
GNU bash, version 4.1.5(1)-release (x86_64-pc-linux-gnu)
Copyright (C) 2009 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software; you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.
@konsolebox
The second command works fine. Thanks.
But why does the first command not work? I'm still confuesd.
First and second commands are all executed with /bin/sh.
$ at -f for_test 14:16
warning: commands will be executed using /bin/sh
job 22 at Thu Aug 29 14:16:00 2013
$ echo "/bin/bash /home/android_su/android/source/linux_learned/for_test" | at 14:19
warning: commands will be executed using /bin/sh
job 23 at Thu Aug 29 14:19:00 2013
Try to use internal functions instead as PATH is not always defined in crontabs and likes:
#!/bin/bash
var1=3
until (( var1 == 0 ))
do
echo "Outer loop: $var1"
var2=1
while (( var2 < 5 ))
do
var3=$(echo "scale=4; $var1 / $var2" | bc)
echo " Inner loop:$var1 / $var2 = $var3"
(( ++var2 ))
done
(( --var1 ))
done >> temp.log.txt
Make sure you run your script as bash as well like this:
echo "/bin/bash /path/to/script.sh" | at 11:10
Or
at 11:10 <<EOF
/bin/bash /path/to/script.sh
EOF