3

I am trying to run a command and store it in a variable.

length=`last | grep foouser | wc -l`

It works fine but when I add a variable to the command it breaks.

value=$1
length=`last | grep $value | wc -l`

How can I get this second example to work by acceptomg a variable?

Improve this question
2
  • What, exactly, breaks? Also, you probably want to use $value in place of $1 in the grep command. Commented Jul 15, 2013 at 13:46
  • Ok yes apologies that was meant to be $value after grep. Commented Jul 15, 2013 at 13:59

2 Answers 2

Reset to default
4

You don't actually need wc: 

length=$(last | grep -c "$value")

You could improve the variable names

num_logins=$(last | grep -c "$username")
Improve this answer
Sign up to request clarification or add additional context in comments.

Comments

4

You should quote your variables properly. If they contain spaces your script might break:

value="$1"
length="$(last | grep "$value" | wc -l)"
Improve this answer

4 Comments

Quoting $value as the argument to grep is important. Quoting the RHS of the two assignments is less so; word-splitting isn't performed, so I'm not sure there's any problem with leaving them unquoted (although it doesn't hurt to quote them, either).
still not luck, I am entering value="foouser" /n length="$(last | grep "$value" | wc -l)" then trying to echo $lenght and it returns nothing @Benoit @chepner
You typed lenght by accident here. Are you mistyping at your terminal as well?
I think you should use brackets properly "${value}".

Start asking to get answers

Find the answer to your question by asking.

Ask question

Explore related questions

See similar questions with these tags.