How do I add IF ELSE to linux variable

Question

I have a variable in my script that displays the user:

OWNER=$(grep 1000:1000: /etc/passwd|cut -f1 -d':')

Output will be something like:

joe

This is fine on a normal server where the os was installed & user was setup during the install. I run into problems on a vps where there is no initial user. I would like to add to the variable IF blank then the output should be "root" but I don't know where to start..

Thankyou

Reinstate Monica Please · Accepted Answer · 2014-01-20 11:34:23Z

4

Something like this

[[ $OWNER == "" ]] && OWNER="root"

or

if [[ $OWNER == "" ]]; then
  OWNER="root"
fi

answered Jan 20, 2014 at 11:34

Reinstate Monica Please

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3 Comments

linuxnoob Over a year ago

Thankyou, Is there a way to have this check all contained in the variable? For example: OWNER=$(grep 1000:1000: /etc/passwd|cut -f1 -d':') [[ $OWNER == "" ]] && OWNER="root"

lmsteffan Over a year ago

Yes : OWNER=$((grep 1000:1000: /etc/passwd || echo "root") | cut -f1 -d":")

Reinstate Monica Please Over a year ago

@linuxnoob I like Imsteffan's suggestion. Alternatively you can just put a ; after the ) in your example.

Michael · Accepted Answer · 2014-01-20 12:16:06Z

1

Why not to check for return value of grep command? If it returns 1 when use root as user, otherwise - cut its result and use it.

LINE="`grep 1000:1000: /etc/passwd`"
[ $? -eq 0 ] && OWNER="`echo "$LINE"|cut -f1 -d":"`" || OWNER=root

edited Jan 20, 2014 at 12:16

answered Jan 20, 2014 at 11:37

Michael

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3 Comments

Reinstate Monica Please Over a year ago

You should quote both $USER and $LINE if you don't want weird expansion (e.g. $USER will always be echoed as having 1-space between word tokens and no leading or trailing spaces, regardless of however many it had from command output)

linuxnoob Over a year ago

Thankyou, That worked perfectly.. Can the full expression be on one line or does it have to be on 2 lines?

Michael Over a year ago

@linuxnoob You can put ; to the end of each line and join them together one-by-one. BTW Do you really need it? It will be harder to understand such line. Instead you can create a function for that purpose. It is much better than combining all the lines into one.

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