#!/bin/bash
s='>ST078050.1 Ovis aries is a sheep chromosome 1, whole genome shotgun sequence
>ST078051.1 Ovis aries is a sheep chromosome 2, whole genome shotgun sequence
>ST078052.1 Ovis aries is a sheep chromosome 3, whole genome shotgun sequence
>ST078053.1 Ovis aries is a sheep chromosome 4, whole genome shotgun sequence
>ST078054.1 Ovis aries is a sheep chromosome 5, whole genome shotgun sequence
>ST078055.1 Ovis aries is a sheep chromosome 6, whole genome shotgun sequence
>ST078056.1 Ovis aries is a sheep chromosome 7, whole genome shotgun sequence
>ST078057.1 Ovis aries is a sheep chromosome 8, whole genome shotgun sequence
>ST078058.1 Ovis aries is a sheep chromosome 9, whole genome shotgun sequence
>ST078059.1 Ovis aries is a sheep chromosome 10, whole genome shotgun sequence
>ST078079.1 Ovis aries is a sheep chromosome X, whole genome shotgun sequence
>ST078080.1 Ovis aries is a sheep chromosome Y, whole genome shotgun sequence'
sed -E 's/^>.*chromosome ([[:alnum:]]+),.*$/>\1/' <<< "$s"
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