skip/README.md

# skip

Skip part of a file.

As `head` will show the top of a file up-to a number of line,
 so `skip` will do the opposite, and not show the top of the file,
 but will show the rest.

Additionally, it can check for whole lines matching,
 or for a token being present on the line.

N.B.: The `skip` crate used to be an implementation of [Skip list](https://en.wikipedia.org/wiki/Skip_list),
by [Luo Jia / Zhouqi Jiang](https://github.com/luojia65) ([source](https://github.com/luojia65/skip)).

## Usage

### Skip a fixed number of lines

This example reads the file from stdin.

```bash
echo "line 1
line 2
line 3
line 4" > input.txt

skip 2 < input.txt
```

Will output:

```text
line 3
line 4
```

### Skip until a number of matching lines

The whole line must match.

This example reads the named file.

```bash
echo "alpha
beta
alpha
alpha
gamma
alpha" > input.txt

skip 2 --line alpha input.txt
```

Will output:

```text
alpha
gamma
alpha
```

### Skip lines until a number of tokens are seen

Looks for a string within a line, counting each occurance.

This example reads the file from stdin.

```bash
echo "Lorem ipsum dolor sit amet, 
consectetur adipiscing elit, 
sed do eiusmod tempor incididunt 
ut labore et dolore magna aliqua. 
Ut enim ad minim veniam, 
quis nostrud exercitation ullamco 
laboris nisi ut aliquip ex ea 
commodo consequat." > input.txt

cat input.txt | skip 2 --token dolor
```

Will output:

```text
Ut enim ad minim veniam, 
quis nostrud exercitation ullamco 
laboris nisi ut aliquip ex ea 
commodo consequat.
```

It matches the first `dolor` on line 1,
 and the second on line 4 as part of the word `dolore`.

### Skip lines until a lines with tokens are seen

Looks for a string within a line, only counting each matching line once.

This example reads the file from stdin.

```bash
echo "Lorem ipsum dolor sit amet, 
consectetur adipiscing elit, 
sed do eiusmod tempor incididunt 
ut labore et dolore magna aliqua. 
Ut enim ad minim veniam, 
quis nostrud exercitation ullamco 
laboris nisi ut aliquip ex ea 
commodo consequat." > input.txt

cat input.txt | skip 4 --token m --ignore-extras
```

Will output:

```text
quis nostrud exercitation ullamco 
laboris nisi ut aliquip ex ea 
commodo consequat. 
```

Without `--ignore-extras`, it would have found the fourth `m` on line 3.

```bash
echo "Lorem ipsum dolor sit amet, 
consectetur adipiscing elit, 
sed do eiusmod tempor incididunt 
ut labore et dolore magna aliqua. 
Ut enim ad minim veniam, 
quis nostrud exercitation ullamco 
laboris nisi ut aliquip ex ea 
commodo consequat." > input.txt

cat input.txt | skip 4 --token m
```

Outputing:

```text
ut labore et dolore magna aliqua. 
Ut enim ad minim veniam, 
quis nostrud exercitation ullamco 
laboris nisi ut aliquip ex ea 
commodo consequat. 
```