Shell 在bash中出现某些nb之前，进行Cat

我有一个文件，例如：

@SRR9110374.1 1/1
GAGTATAAAGAAGAAAGTAAATCTCGGTTCGTCTCTTCATCGAGAGAAATGTCGACGAGAAAAAAAAAACAAGGGCTCATTTAAAGCCTTTCAAATCCT
+
BBBBBFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFBFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF
@SRR9110374.2 2/1
ATATGGAACAAGTTAAAAAAAATAAAAAGCAAAGAAATAATGTTTTGTCATCGAAAGTGTCGACATAAAAACAGGTTGGCATCTGGCCTGGTATCTCA
+
BBBBBFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF<BFFFFFFF<FFFFFFFFFFF
@SRR9110374.3 3/1
NTATAACCGTATCAAAGAAGTTTACCCCGAGAGAAGCACGCAGTTTCCCACAGGTAATTTTCTCACAAGCGAGAGAAACATCATACCGCAATCAGGAAC
+
#<<BBFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFBFFFFFFFFFFFFFF
@SRR9110374.4 4/1
GATAAAGAATATAGCTATGTATAGCCGGGATATATTAAGTGATTGAAATATCTCTTAGAAATCCATAGAATAGTAGTGTATCGAATAGGAGGAAGCGAAA
+
BBBBBFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF
@SRR9110374.5 5/1
CTTCCAATGCTTGCCAAAGTTCATTGTCGTTGTAATTATCGAAAGGATCTAAATTCTTTCTCAACGAACCCGAGAATAGGAAGGGTTCTTGAGGAATTAT
+
BBBBBFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF/FFFFFFFFFFFFFFFFFFBFFF/FFF
@SRR9110374.6 6/1
ACCGATAATCTTTCCTTCTCAAGAATTTTGTTAATATTCCACATTTTTAAATAGATTTCATTTCTCTCTCTCTTTCTCTCTCTTTTTCTTGTCCTCGATG
+
BBBBBFFFFFFFFFFFFFFFFFFFFFBFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFBFFBFFFF///FF
@SRR9110374.7 7/1
GTTGTGCTGAGAATGTTAATAAATTACAAAATGTTATCACTAACTTGGAAATATTCGAATCGACAGATATCGCGTTTGTCGTGTTGTATTAATATATTC
+
BBBBBFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF
@SRR9110374.8 8/1
GTCATAGAACGGGGGAGGGGAGGAAGAAGAAAGGAAGGGAAAAAAACGAGAGAGAGAGAGGGGATTACGCTCGCCGTTCGAATCGTTAGGCGTCCGTTT
+
BBBBBFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFBFFFFFFFFFFFFFFFFFFBBFBBFF
@SRR9110374.9 9/1
AATTATTATTTAATCGACGCGTCTATCGATAAATCATCCTCGAATGCTAAGCAAAACTGAACTTCCGCAAATATTGCACACGAAACGTTGAAACAAAG
+
BBBBBFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF

我应该得到：

@SRR9110374.1 1/1
GAGTATAAAGAAGAAAGTAAATCTCGGTTCGTCTCTTCATCGAGAGAAATGTCGACGAGAAAAAAAAAACAAGGGCTCATTTAAAGCCTTTCAAATCCT
+
BBBBBFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFBFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF
@SRR9110374.2 2/1
ATATGGAACAAGTTAAAAAAAATAAAAAGCAAAGAAATAATGTTTTGTCATCGAAAGTGTCGACATAAAAACAGGTTGGCATCTGGCCTGGTATCTCA
+
BBBBBFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF<BFFFFFFF<FFFFFFFFFFF
@SRR9110374.3 3/1
NTATAACCGTATCAAAGAAGTTTACCCCGAGAGAAGCACGCAGTTTCCCACAGGTAATTTTCTCACAAGCGAGAGAAACATCATACCGCAATCAGGAAC
+
#<<BBFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFBFFFFFFFFFFFFFF
@SRR9110374.4 4/1
GATAAAGAATATAGCTATGTATAGCCGGGATATATTAAGTGATTGAAATATCTCTTAGAAATCCATAGAATAGTAGTGTATCGAATAGGAGGAAGCGAAA
+
BBBBBFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF

---

Ps：真正的文件非常大，所以我应该得到一个适合的方法，这将是很好的。

请您尝试以下内容

Nb_occurence=4
awk -v nb_occur="$Nb_occurence" '
BEGIN{
  occur=0
}
/@/{
  occur++
}
occur>nb_occur{
  exit
}
occur
' Input_file

Ps：真实的文件非常大，所以我应该得到一个适合的方法 那太好了

要加快输入文件读取速度，请执行以下操作：

---

为了加快您对输入文件的处理，我使用了exit，因此，一旦您提到的读取次数完成，它将尽快从输入文件中出来，因为我们不需要进一步读取它，因此它应该比您的解决方案更快。

请尝试以下操作

Nb_occurence=4
awk -v nb_occur="$Nb_occurence" '
BEGIN{
  occur=0
}
/@/{
  occur++
}
occur>nb_occur{
  exit
}
occur
' Input_file

Ps：真实的文件非常大，所以我应该得到一个适合的方法 那太好了

要加快输入文件读取速度，请执行以下操作：

为了加快您对输入文件的处理速度，我使用了exit，因此，一旦您提到的读取次数完成，它将尽快从输入文件中出来，因为我们不需要进一步读取它，因此它应该比您的解决方案快。

您应该以这种方式重写awk：

awk -v occurence=$Nb_occurence 'BEGIN{ found=0} /@/{found=found+1} {if ( found < occurence ) print }' file

而且您不需要cat，awk可以读取文件

您应该通过以下方式重写您的awk：

awk -v occurence=$Nb_occurence 'BEGIN{ found=0} /@/{found=found+1} {if ( found < occurence ) print }' file

您不需要cat，awk可以读取文件

另一个awk：

$ awk -v n=4 '/@/&&!n--{exit}1' file

输出：

@SRR9110374.1 1/1
GAGTATAAAGAAGAAAGTAAATCTCGGTTCGTCTCTTCATCGAGAGAAATGTCGACGAGAAAAAAAAAACAAGGGCTCATTTAAAGCCTTTCAAATCCT
+
BBBBBFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFBFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF
@SRR9110374.2 2/1
ATATGGAACAAGTTAAAAAAAATAAAAAGCAAAGAAATAATGTTTTGTCATCGAAAGTGTCGACATAAAAACAGGTTGGCATCTGGCCTGGTATCTCA
+
BBBBBFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF<BFFFFFFF<FFFFFFFFFFF
@SRR9110374.3 3/1
NTATAACCGTATCAAAGAAGTTTACCCCGAGAGAAGCACGCAGTTTCCCACAGGTAATTTTCTCACAAGCGAGAGAAACATCATACCGCAATCAGGAAC
+
#<<BBFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFBFFFFFFFFFFFFFF
@SRR9110374.4 4/1
GATAAAGAATATAGCTATGTATAGCCGGGATATATTAAGTGATTGAAATATCTCTTAGAAATCCATAGAATAGTAGTGTATCGAATAGGAGGAAGCGAAA
+
BBBBBFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF

另一个awk：

$ awk -v n=4 '/@/&&!n--{exit}1' file

输出：

@SRR9110374.1 1/1
GAGTATAAAGAAGAAAGTAAATCTCGGTTCGTCTCTTCATCGAGAGAAATGTCGACGAGAAAAAAAAAACAAGGGCTCATTTAAAGCCTTTCAAATCCT
+
BBBBBFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFBFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF
@SRR9110374.2 2/1
ATATGGAACAAGTTAAAAAAAATAAAAAGCAAAGAAATAATGTTTTGTCATCGAAAGTGTCGACATAAAAACAGGTTGGCATCTGGCCTGGTATCTCA
+
BBBBBFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF<BFFFFFFF<FFFFFFFFFFF
@SRR9110374.3 3/1
NTATAACCGTATCAAAGAAGTTTACCCCGAGAGAAGCACGCAGTTTCCCACAGGTAATTTTCTCACAAGCGAGAGAAACATCATACCGCAATCAGGAAC
+
#<<BBFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFBFFFFFFFFFFFFFF
@SRR9110374.4 4/1
GATAAAGAATATAGCTATGTATAGCCGGGATATATTAAGTGATTGAAATATCTCTTAGAAATCCATAGAATAGTAGTGTATCGAATAGGAGGAAGCGAAA
+
BBBBBFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF

---

这样做，您将读取整个文件，如果文件很大，这可能会变得有害！看一看！正当但这是操作的方式。我只是调整他/她的解决方案。这样做，您将读取整个文件，如果文件很大，这可能会变得有害！看一看！正当但这是OP的方式。我只是调整他/她的解决方案。