Obtain output from a bash command in Ruby

Question

I'm trying to obtain the output of a bash command. More precisely, I need to store the number of lines that contains a string in a file:

variable_name = AAAAAAA
PATH_TO_SEARCH = .
COMMAND = "grep -R #{variable_name} #{PATH_TO_SEARCH} | wc -l"

To execute the command I tried both methods:

num_lines = %x[ #{COMMAND} ]
num_lines = `#{COMMAND}`

but the problem is: In "num_lines" I have 1) the number of lines that contain the string (OK!) and 2) output from grep like "grep: /home/file_example.txt: No such file or directory" (NO!). I would like to store just the first output.

Do you mean the first output as the output for the first file only? — konsolebox
– konsolebox, Commented Jul 16, 2014 at 12:20

Community · Accepted Answer · 2017-05-23 11:57:51Z

1

Looks like you may just need to suppress the error messages.

"You can use the -s or --no-messages flag to suppress errors." found from How can I have grep not print out 'No such file or directory' errors?

edited May 23, 2017 at 11:57

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answered Jul 16, 2014 at 12:12

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1 Comment

simonwo Over a year ago

More generally, use &>/dev/null after the command and it's arguments to supress all output.

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