Trying to use the output of Grep -E in if statement in bash script

Question

I am trying to use the output of $mount to check whether there are network mount points and if so, do what is stated. Instead, I keep getting the else statement no matter what I try.

If I run mount | egrep 'cifs|nfs|rpc' mount | egrep 'cifs|nfs|rpc' on command line, I see that there are network mounts. How do I do this in a script? I CANNOT figure it out after much trial and error and want to pull my hair out.

Red Hat 6.8 is my OS but will need it to work for 6.x and 7.x

Sample output when run at command line:

~# mount | egrep 'cifs|nfs|rpc' 

sunrpc on /var/lib/nfs/rpc_pipefs type rpc_pipefs (rw)
machine.example.com:/export/home/x/ICD103 on
/mnt/ICD103 type nfs(rw,soft,int,rsize=8192,wsize=8192,sloppy,vers=4,addr=xx.xxx.xxx.xx,clientaddr=10.xxx.xxx.xxx)
//new-devstore/Stable/Assets on /mnt/assets type cifs (rw)

mount=$(mount | egrep 'cifs|nfs|rpc')

if $mount; then
    mount > $destBAK/mount.txt;
    cp -p /etc/auto.cifs > $destBAK 2>/dev/null;
    cp -p /etc/auto.master > $destBAK 2>/dev/null;
    cp -p /root/.smbauth > $destBAK 2>/dev/null;
    cp -p /etc/fstab > $destBAK 2>/dev/null;
else
    echo "No Network Mount"
fi

Output after running ./backup.sh

~# ./backup.sh
Making backup directory /tmp/BAK_2017-10-13 now 
Copying files to /tmp/BAK_2017-10-13
./backup.sh: line 34: sunrpc: command not found
No Network Mount

Answer 1

Saying

if $mount

will try to execute the value of $mount. It's basically like saying

if "foo"; then echo ok; else echo no; fi

Unless your string has a successfully executable value, it will always throw an error and give you the else .

Why assigning to a var?

if mount | egrep 'cifs|nfs|rpc'
then ...

will use the return from the egrep.

If you do need to catch and save the output collectively, then use

if [[ -n "$mount" ]] # tests string for nonzero length
then ...

If you need the output lines individually, try

hit=0
mount | egrep 'cifs|nfs|rpc' |
  while read mnt
  do hit=1
     # ... all your mount code above
  done
if (( hit )) # math evaluation
then : any remaining stuff you might need to do
else echo "No Network Mount"
fi

update --

an attempt to re-engineer what you want:

tmp=/tmp/mount.txt
mount > $tmp
if egrep -q 'cifs|nfs|rpc' $tmp
then mv $tmp $destBAK
     cp -p /etc/auto.cifs $destBAK
     cp -p /etc/auto.master $destBAK
     cp -p /root/.smbauth $destBAK
     cp -p /etc/fstab $destBAK
else
    echo "No Network Mount"
    rm $tmp
fi

This should work. I took off all the stderr redirections because you should know about errors, and ideally handle them, but at least here it will report them.

This doesn't work for you?

Answer 2

it is because of the redirection in your code. use double 'greater than' signs, >>, this will append instead of overwrite each cp statement in your code. Something like this should work:

if $mount; then
    mount > $destBAK/mount.txt;
    cp -p /etc/auto.cifs >> $destBAK 2>/dev/null;
    cp -p /etc/auto.master >> $destBAK 2>/dev/null;
    cp -p /root/.smbauth >> $destBAK 2>/dev/null;
    cp -p /etc/fstab >> $destBAK 2>/dev/null;
else
    echo "No Network Mount"
fi