Database Reference
In-Depth Information
but always include the header in the output? Or what if we only wanted to uppercase
the values of a specific column using
tr
and leave the other columns untouched?
There are multistep workarounds for this, but they're very cumbersome. We have
something better. In order to leverage ordinary command-line tools for CSV, we'd like
to introduce you to three command-line tools, aptly named:
body
(Janssens, 2014),
header
(Janssens, 2014), and
cols
(Janssens, 2014).
Let's start with the first command-line tool:
body
. With
body
, you can apply any
command-line tool to the body of a CSV file (i.e., everything excluding the header).
For example:
$
echo
-e
"value\n7\n2\n5\n3"
| body sort -n
value
2
3
5
7
It assumes that the header of the CSV file only spans one row. Here's the source code
for completeness:
#!/usr/bin/env bash
IFS
=
read
-r header
printf
'%s\n'
"$header"
$@
It works like this:
Take one line from standard input and store it as a variable named
$header
.
Print out the header.
Execute all the command-line arguments passed to
body
on the remaining data.
Here's another example. Imagine that we count the lines of the following CSV file:
$
seq 5 | header -a count
count
1
2
3
4
5
With
wc -l
, we can count the number of all lines:
$
seq 5 | header -a count | wc -l
6
If we only want to consider the lines in the body (so everything except the header),
we simply add
body
:
