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pv:tldr:883ae
This command is used to filter the contents of a big_text_file based on a specific pattern and save the filtered output to a separate file.
Let's break down the command step by step:
-
pv
: This is the command-line tool used to monitor the progress of data being passed through a pipeline. It stands for "pipe viewer". -
-cN
: These are pv's options to create and name a custom counter. -
in ${big_text_file}
: This part specifies the input source file that we want to filter.${big_text_file}
represents a placeholder for the actual name or path of the file. -
|
: This is the standard pipe operator in a Unix-like shell, it takes the output of the previous command and feeds it as input to the next command. -
grep ${pattern}
: This command searches for lines in the input that match a specific pattern.${pattern}
represents a placeholder for the pattern you are searching for. -
|
: Another pipe operator to pass the output of the previous command as input to the next command. -
pv -cN out
: Here,pv
is used again to create and name another custom counter. This step allows us to monitor the progress of the filtered output. -
>
: This is the output redirection operator. It takes the output of the previous command and redirects it to the specified file. -
${filtered_file}
: This represents a placeholder for the name or path of the file where the filtered output will be saved.
To summarize, this command reads the content of ${big_text_file}
, searches for lines that match ${pattern}
, and saves the filtered output to ${filtered_file}
. The two instances of pv
are used to monitor the progress of the data flowing through the pipeline.