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# Keystroke-savers

## Short format specifiers, including --c2p

In our examples so far, we've often made use of `mlr --icsv --opprint` or `mlr --icsv --ojson`. These are such frequently occurring patterns that they have short options like `--c2p` and `--c2j`:

<pre class="pre-highlight-in-pair">
<b>mlr --c2p head -n 2 example.csv</b>
</pre>
<pre class="pre-non-highlight-in-pair">
color  shape    flag k index quantity rate
yellow triangle true 1 11    43.6498  9.8870
red    square   true 2 15    79.2778  0.0130
</pre>

<pre class="pre-highlight-in-pair">
<b>mlr --c2j head -n 2 example.csv</b>
</pre>
<pre class="pre-non-highlight-in-pair">
[
{
  "color": "yellow",
  "shape": "triangle",
  "flag": "true",
  "k": 1,
  "index": 11,
  "quantity": 43.6498,
  "rate": 9.8870
},
{
  "color": "red",
  "shape": "square",
  "flag": "true",
  "k": 2,
  "index": 15,
  "quantity": 79.2778,
  "rate": 0.0130
}
]
</pre>

You can get the full list [here](file-formats.md#data-conversion-keystroke-savers).

## File names up front, including --from

Already, we saw that you can put the filename first using `--from`. When you're interacting with your data at the command line, this makes it easier to up-arrow and append to the previous command:

<pre class="pre-highlight-in-pair">
<b>mlr --c2p --from example.csv sort -nr index then head -n 3</b>
</pre>
<pre class="pre-non-highlight-in-pair">
color  shape  flag  k  index quantity rate
purple square false 10 91    72.3735  8.2430
yellow circle true  9  87    63.5058  8.3350
yellow circle true  8  73    63.9785  4.2370
</pre>

<pre class="pre-highlight-in-pair">
<b>mlr --c2p --from example.csv sort -nr index then head -n 3 then cut -f shape,quantity</b>
</pre>
<pre class="pre-non-highlight-in-pair">
shape  quantity
square 72.3735
circle 63.5058
circle 63.9785
</pre>

If there's more than one input file, you can use `--mfrom`, then however many file names, then `--` to indicate the end of your input-file-name list:

<pre class="pre-highlight-non-pair">
<b>mlr --c2p --mfrom data/*.csv -- sort -n index</b>
</pre>

Alternatively, you may place filenames within another file, one per line:

<pre class="pre-highlight-non-pair">
<b>cat data/filenames.txt</b>
</pre>

<pre class="pre-highlight-non-pair">
<b>mlr --c2p --files data/filenames.txt cat</b>
</pre>

## Shortest flags for CSV, TSV, and JSON

The following have even shorter versions:

* `-c` is the same as `--csv`
* `-t` is the same as `--tsv`
* `-j` is the same as `--json`

I don't use these within these documents, since I want the docs to be self-explanatory on every page, and
I think `mlr --csv ...` explains itself better than `mlr -c ...`. Nonetheless, they're always there for you to use.

## .mlrrc file

If you want the default file format for Miller to be CSV, you can put `--csv` on a line by itself in your `~/.mlrrc` file. Then, instead of `mlr --csv cat example.csv` you can just do `mlr cat example.csv`. This is just a personal default, though, so `mlr --opprint cat example.csv` will use default CSV format for input, and PPRINT (tabular) for output.

You can read more about this at the [Customization](customization.md) page.

## Scripts and mlr -s

Suppose you are often doing something like

<pre class="pre-non-highlight-non-pair">
mlr --csv \
filter ‘$quantity > 100’ then \
count-distinct -f category then \
fraction -f count \
filename-which-varies.csv
</pre>

Typing this out can get a bit old if the only thing that changes for you is the filename.

See [Scripting with Miller](scripting.md) for some keystroke-saving options.
