XSV is an extremely fast CLI utility to process csv/tsv/psv files. Extremely helpful to automate data extraction, format conversions, filters etc.

It comes with an extensive man page and website also has great documentation. Still, noting down some of the common ways I use it below.

First, download from the tool's site at or brew install xsv

Inspect file

#field type, statistics
xsv stats sample.csv 

#count records
xsv count sample.csv 

#flatten file and show record by record
xsv flatten sample.csv

#nicely readable flat output for statistics
xsv stats sample.csv|xsv flatten
#or show as nicely aligned table
xsv stats sample.csv|xsv table

#create an index file for fast processing. Very useful on large files. Not needed for smaller files
#and when you update the file, you need recreate the index file too.
xsv index sample.csv

File format conversion

Best part is that you don't have to worry about header rows, escaping characters etc.

#csv to psv (pipe separated)
xsv fmt -t \| sample.csv
#tab separated to csv
xsv fmt -d "^I" sample.tsv
#tsv to psv
xsv fmt -d \| -t "^I" sample.psv

Note that "^I" indicates a TAB character - you can type that in terminal by CTRL-V-I.

Split & Merge files

# split file into multiple files by a column - aka partition
#   adds one file per value of office field in directory t/
xsv partition office t/ employees.csv  

#split the file every 1000 records into directory t/
xsv split -s 1000 t/ employees.csv

#merge rows from multiple files without duplicating header record
xsv cat rows t/*.csv

Select Data

#random select 4 records
xsv sample 4 employees.csv

# select two columns by name
xsv select department,empid employees.csv
# select first and third column
xsv select 1,3 employees.csv
# select first to second column
xsv select 1-2 employee.csv 
# select first and third column in another order
xsv select 3,1 employees.csv

# and sort output in reverse order of department
xsv select 3,1 employees.csv.csv|xsv sort -R -s department 

# extract 2nd row to 4th row
xsv slice -s 2 -e 5 employees.csv
# extract 3 rows starting from second row
xsv slice -s 2 -l 3 employees.csv

# filter by regex "galore" ignoring case
xsv search -i "galore" employees.csv
# filter by regex NOT "galore" ignoring case
xsv search -i -v "galore" employees.csv

Joins

# inner join on cities.city = employees.office
xsv join city cities.csv office employees.csv
# left and right joins
xsv join --left city cities.csv office employees.csv
xsv join --right city cities.csv office employees.csv