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mlr:tldr:ead79
The command is using the mlr
tool to filter a CSV file that has been compressed with gzip.
Here is the breakdown of the command:
-
mlr
: This is the command to invoke themlr
tool, which stands for "Miller". Miller is a command-line tool for processing and manipulating structured text files, like CSV. -
--prepipe 'gunzip'
: This option specifies that the input file should first be decompressed usinggunzip
. So, the input file, which is specified as${example-csv-gz}
, is expected to be a gzip-compressed CSV file. -
--csv
: This option informsmlr
that the input file is in CSV format. -
filter -S '$${fieldName} =~ "${regular_expression}"'
: This is the filtering operation being applied bymlr
. Thefilter
command is used to selectively include or exclude records from the input data. The-S
flag is used to preserve the input order of records.Inside the single quotes, the filter expression is specified. The
${fieldName}
is a placeholder for a field name in the input data which you need to replace with an actual field name. The=~
operator is the "matches-regex" operator, which checks if the field value matches the specified regular expression${regular_expression}
. -
${example-csv-gz}
: This is the path or filename of the input file. It should be replaced with the actual path or filename of your gzip-compressed CSV file.
In summary, the command takes a gzip-compressed CSV file as input, decompresses it, and filters the records based on a specified field name and regular expression.