Im writing a script, but it is throwing some errors when something is not found, i need ignore those error.i mean when i run the script it should display positive results if any errors should not display.

#!/bin/sh
boot=$(ls /bootpool | grep boot | awk 'NR==1{print $1}')
data=$(ls /datapool | grep boot | awk 'NR==1{print $1}')
echo "boot"
if [ "$boot" == "boot" ]
then echo "boot" pass=$(grep rootpw /bootpool/boot/loader.conf| grep -o '".*"' | sed 's/"//g' | awk 'BEGIN { ORS = " " } { print }')
elif [ "$data" == "boot" ]
then pass=$(grep rootpw /datapool/boot/loader.conf| grep -o '".*"' | sed 's/"//g' | awk 'BEGIN { ORS = " " } { print }')
fi
if [ $pass == edjos ]
then echo "You are at default password. kindly change the password" oldpass=$(grep root /etc/master.passwd | awk 'NR==1 { print $1 }' | cut -d ':' -f 2 | sed 's/\$/\%/g') passwd newpass=$(grep root /etc/master.passwd | awk 'NR==1 { print $1 }' | cut -d ':' -f 2 | sed 's/\$/\%/g') if [ "$newpass" != "$oldpass" ] then if [ "$boot" == "boot" ] then sed -i.bak '/ /bootpool/boot/loader.conf sed -i.bak '/ /bootpool/boot/loader.conf echo mfsbsd.rootpwhash=\"$newpass\" >> /bootpool/boot/loader.conf echo "Great! password updated successfully" elif [ "$data" == "boot" ] then sed -i.bak '/ /datapool/boot/loader.conf sed -i.bak '/ /datapool/boot/loader.conf echo mfsbsd.rootpwhash=\"$newpass\" >> /datapool/boot/loader.conf echo "Great! password updated successfully" fi fi else echo "Great! you are having authorised password"
fi

2

1 Answer

You can put 2>/dev/null behind a command to suppress errors:

ls /home/cas/thisfolderdoesntexist -> error

ls /home/cas/thisfolderdoesntexist 2>/dev/null -> no output because error is suppressed.

You can also put 2>/dev/null behind a script to run the complete script with errors suppressed:

./script.sh 2>/dev/null

What your doing is redirecting (>) errors (2) to /dev/null. Every piece of data (in this case the output of your command(s)/script) that is redirected to /dev/null will be completely ignored. See it as a trash can for data.

---

Edit:2>/dev/null suppresses the output of the command, not the complete pipe. In the example that you gave, you're supressing errors from the awk command. If the error is comming from the ls command, do the following (this will suppress errors from the ls command):

ls /bootpool 2>/dev/null | grep boot | awk 'NR==1{print $1}'

If the error is comming from the grep command:

ls /bootpool | grep boot 2>/dev/null | awk 'NR==1{print $1}'

I think you get it now.

A good thing to remember:

1 = stdout = normal output of a command

2 = stderr = error output of a command

0 = stdin = input to a command (this isn't usefull for redirecting, more for logging)

---

I also improved your script (using shellcheck, you can install it or use their online tool link):

#!/bin/sh
boot=$(find /bootpool/*boot* 2>/dev/null | sed "s|/.*/||")
data=$(find /datapool/*boot* 2>/dev/null | sed "s|/.*/||")
echo "boot"
if [ "$boot" = "boot" ]
then echo "boot" pass=$(grep rootpw /bootpool/boot/loader.conf | grep -o '".*"' | sed 's|"||g' | awk 'BEGIN { ORS = " " } { print }')
elif [ "$data" = "boot" ]
then pass=$(grep rootpw /datapool/boot/loader.conf | grep -o '".*"' | sed 's|"||g' | awk 'BEGIN { ORS = " " } { print }')
else echo "Couldn't find boot in bootpool nor datapool" exit
fi
if [ "$pass" = edjos ]
then echo "You are at default password. kindly change the password" oldpass=$(grep root /etc/master.passwd | awk 'NR==1 { print $1 }' | cut -d ':' -f 2 | sed 's/\$/\%/g') passwd newpass=$(grep root /etc/master.passwd | awk 'NR==1 { print $1 }' | cut -d ':' -f 2 | sed 's/\$/\%/g') if [ "$newpass" != "$oldpass" ] then if [ "$boot" = "boot" ] then sed -i.bak '/ /bootpool/boot/loader.conf sed -i.bak '/ /bootpool/boot/loader.conf echo "mfsbsd.rootpwhash=\"$newpass\"" >> /bootpool/boot/loader.conf echo "Great! password updated successfully" elif [ "$data" = "boot" ] then sed -i.bak '/ /datapool/boot/loader.conf sed -i.bak '/ /datapool/boot/loader.conf echo "mfsbsd.rootpwhash=\"$newpass\"" >> /datapool/boot/loader.conf echo "Great! password updated successfully" fi fi
else echo "Great! you are having authorised password"
fi

1. You were using == but /bin/sh doesn't make use of that. Only =. When you use /bin/bash, == will actually become usefull. But as you don't, you need to use =.
2. I changed the way you set the boot and data variables. The way you did it was inefficient.
3. When both $boot and $data are empty, the script will catch it instead of letting you continue. This is handy because in your second if statement, when $oldpass and $newpass aren't equal, it depends on either $boot or $data to contain "boot". But what if they don't? That's what the else is for in the first if-statement.
4. Putting "" around variables. echo $var -> echo "$var"

4

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