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Homework and Emergencies Homework & Coursework Questions Help needed - UNIX command
# 1  
Old 04-23-2019
Help needed - UNIX command
The 'env' command prints out all of the environment variables and their values.
Come up with a command that prints a list of environment variables whose names
end with either 'NAME', 'DIR' or 'PATH'.

What I've tried.
Code:
$ env | grep '[NAME, DIR, PATH]'

Although it highlights the part of the variables it does not list them as it should. It actually prints the whole lines including the variables. Not sure what I'm missing.

University Of Technology Sydney, Unix Systems Programming
# 2  
Old 04-24-2019
Hello edujs7,

Could you please try following.

Code:
env | awk 'BEGIN{FS="="} $1 ~ /.*(NAME$|DIR$|PATH$)/'

Thanks,
R. Singh
This User Gave Thanks to RavinderSingh13 For This Post:
edujs7
# 3  
Old 04-24-2019
Try:
Code:
env | grep -E '^(NAME|DIR|PATH)='

# 4  
Old 04-24-2019
Quote:
Originally Posted by Scrutinizer
Try:
Code:
env | grep -E '^(NAME|DIR|PATH)='

This gives me the below; seems to be only picking up "PATH=" and nothing else.

Code:
$ env | egrep '^(NAME|DIR|PATH)='

PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin

--- Post updated at 04:06 AM ---

Thank you RavinderSingh13

I get the below output - however, I believe I only need the Variables listed and nothing else.

Code:
env | awk 'BEGIN{FS="="} $1 ~ /.*(NAME$|DIR$|PATH$)/'

USERNAME=eduardo
MANDATORY_PATH=/usr/share/gconf/ubuntu.mandatory.path
TEXTDOMAINDIR=/usr/share/locale/
DEFAULTS_PATH=/usr/share/gconf/ubuntu.default.path
WINDOWPATH=2
LOGNAME=eduardo
XDG_RUNTIME_DIR=/run/user/1000
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin

# 5  
Old 04-24-2019
Quote:
Originally Posted by edujs7
Thank you RavinderSingh13
I get the below output - however, I believe I only need the Variables listed and nothing else.
Code:
env | awk 'BEGIN{FS="="} $1 ~ /.*(NAME$|DIR$|PATH$)/'

Hello edujs7,

In case you want to have only variable names then try following.
Code:
env | awk 'BEGIN{FS="="} $1 ~ /.*(NAME$|DIR$|PATH$)/{print $1}'

Thanks,
R. Singh
This User Gave Thanks to RavinderSingh13 For This Post:
edujs7
# 6  
Old 04-24-2019
In a regular expression (RE) the ^ means the beginning of the line; together with the = it enforces an exact match. Omit the ^ and it must only end with the given pattern.

$1 ~ /.*(NAME$|DIR$|PATH$)/ is correct, because the $1 field is = delimited, and in a RE the $ enforces the end of the field. The .* means any characters but is not needed here because any leading characters are always permitted in a RE (unless there is a ^ anchor). So it is optimized $1 ~ /NAME$|DIR$|PATH$/ or with a common $ anchor $1 ~ /(NAME|DIR|PATH)$/.
Last edited by MadeInGermany; 04-24-2019 at 04:03 AM..
This User Gave Thanks to MadeInGermany For This Post:
RavinderSingh13
# 7  
Old 04-24-2019
Thanks so much - that worked Smilie

Sorry to be a pain but would you please be able to explain what the actual command does Smilie - and wouldn't egrep work for this?
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