CODEWITHSUNDEEP
linuxbashshell
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Reputation: 307

Is it possible to pipe multiple commands in an 'if' statement?

Part of a script I'm writing needs to check various text files for the same strings. Before I just had to check one file so I had a long list of strings within cateogies to search for which are defined as variables. Later on in the script the variabled are called and output to the screen if there is a match:

category_1=$(sudo zcat myfile | egrep -c 'Event 1|Event 2|Event 3')

category_2=$(sudo zcat myfile | egrep -c 'Event 4|Event 5|Event 6')

category_3=$(sudo zcat myfile | egrep -c 'Event 7|Event 8|Event 9')

...

echo Category 1

if [[ $category_1 -ge 2 ]];then

            echo There were $category_1 events

elif [[ $category_1 -eq 1 ]]; then

            echo There was $category_1 event

fi

etc, etc...

Now I need to change it so that I can check the grepped strings against multiple text files. I've tried to define the new files as variables and pipe them in the if statement with the grep variable to no avail:

category_1=$(egrep -c 'Event 1|Event 2|Event 3')

category_2=$(egrep -c 'Event 4|Event 5|Event 6')

category_3=$(egrep -c 'Event 7|Event 8|Event 9')


myfile=$(sudo zcat myfile)

myfile2=$(sudo zcat myfile2)

myfile3=$(sudo zcat myfile3)

...

echo Category 1 - Myfile



if [[ myfile | $category_1 -ge 2 ]];then

            echo There were $category_1 events in myfile

elif [[ myfile | $category_1 -eq 1 ]]; then

            echo There was $category_1 event in myfile

fi

It seems that I can't pipe commands in an if statement.

Upvotes: 18

Views: 35918

Answers (3)

Nicki Johanna
Nicki Johanna

Reputation: 1

You could instead use a command such as: if [ "$house" = "nice" ]||[ "$house" = "bad" ] then... to do the job

Upvotes: 0

Igor Chubin
Igor Chubin

Reputation: 64563

You can use pipes in if, but you mix two things. You use $category_1 with pipe; and $category_1 is not a command. You can use a command substitution instead of the variable.

if [[ `sudo zcat myfile | egrep -c 'Event 1|Event 2|Event 3')` -ge 2 ]];then

and so on.

You can also use variables instead of commands, but it will be a little bit strange.

Upvotes: 1

choroba
choroba

Reputation: 241838

Use $(...) to capture output of a command into a string:

if  [[ $(sudo zcat myfile1 | egrep -c 'Event 1|Event 2|Event 3') -ge 2 ]] ; then

Upvotes: 25

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