What is output in theory only for the below commands

debkumar · 10-08-2018, 04:15 AM

#cat /etc/fstab |egrep -i ""
#cat /etc/fstab |egrep -i "/"
# /opt/gs-utils/inq -hba

l0f4r0 · 10-08-2018, 04:42 AM

I invite you to enter:

Code:

man egrep

You will find what option "-i" stands for and what its purpose is (see "Matching Control" section).

NB1: as egrep is the same as grep -E, you may find your answers with:

Code:

man grep

as well...

NB2:

Code:

egrep ""

will return each line as your pattern is empty.

NB3: as is, your commands will return nothing as they are prefixed with '#' (sign to indicate a comment).

lougavulin · 10-08-2018, 07:16 AM

Why don't you try the first 2 yourself ? They just read file, do not change anything, no risk.

The third one, I don't know what it is.

And as said by l0f4r0, if those commands are in a script, they are commented, nothing will happen.

pan64 · 10-08-2018, 07:22 AM

I don't really like if you modify the original post after the first answer. That may lead to conflicts...
I don't know if you [want to] use it as root (that is your #) or those lines are commented and/or copied from somewhere. Can you please add some more details. Is this your homework?

fatmac · 10-08-2018, 08:00 AM

Likely to be homework as it's a first post, & all about one command.

BW-userx · 10-08-2018, 08:06 AM

yeah, I was going to ask what number is that one?
if you got a liunx box, then try issuing the command to give you a good idea on what that answer should be....

Code:

userx@manjaroieo:~
$ cat /etc/fstab |egrep -i "/"
# /etc/fstab: static file system information.
UUID=9314724d-c954-4d76-aedf-4e0cb17c2705 /              ext4    defaults,noatime,discard 0 1
UUID=ffb281eb-7a82-45f7-b444-9d37e0dfd6bb /home          ext4    defaults,noatime 0 2
UUID=47E540DF2714E6A5                     /media/ntfs1   ntfs    defaults,noatime 0 2
UUID=eb3b4090-d341-4f20-927d-c5414254b767 /media/data1   ext4    defaults,noatime 0 2
tmpfs                                     /tmp           tmpfs   defaults,noatime,mode=1777 0 0


then loop it up
$ man egrep

looking to see what that '-i' does, and figuring out what does the pattern in the quotes do..

then experiment with it

userx@manjaroieo:~
$ cat /etc/fstab |egrep -i "UUID"
# be used with UUID= as a more robust way to name devices that works even if
UUID=9314724d-c954-4d76-aedf-4e0cb17c2705 /              ext4    defaults,noatime,discard 0 1
UUID=ffb281eb-7a82-45f7-b444-9d37e0dfd6bb /home          ext4    defaults,noatime 0 2
UUID=47E540DF2714E6A5                     /media/ntfs1   ntfs    defaults,noatime 0 2
UUID=eb3b4090-d341-4f20-927d-c5414254b767 /media/data1   ext4    defaults,noatime 0 2

ondoho · 10-09-2018, 01:40 AM

also, useless use of cat.

Code:

egrep -i "/" /etc/fstab

does the same (but doesn't really make sense).