循环遍历Bash中的文件内容 [英] Looping through the content of a file in Bash

问题描述

如何使用 Bash 迭代文本文件的每一行？

How do I iterate through each line of a text file with Bash?

使用此脚本：

echo "Start!"
for p in (peptides.txt)
do
    echo "${p}"
done

我在屏幕上显示此输出：

I get this output on the screen:

Start!
./runPep.sh: line 3: syntax error near unexpected token `('
./runPep.sh: line 3: `for p in (peptides.txt)'

（后来我想做一些比{code> $ p 更复杂的事情而不仅仅是输出到屏幕。）

(Later I want to do something more complicated with $p than just output to the screen.)

环境变量 SHELL 是（来自env）：

The environment variable SHELL is (from env):

SHELL=/bin/bash

/ bin / bash --version 输出：

GNU bash, version 3.1.17(1)-release (x86_64-suse-linux-gnu)
Copyright (C) 2005 Free Software Foundation, Inc.

cat / proc / version 输出：

Linux version 2.6.18.2-34-default (geeko@buildhost) (gcc version 4.1.2 20061115 (prerelease) (SUSE Linux)) #1 SMP Mon Nov 27 11:46:27 UTC 2006

文件peptides.txt包含：

The file peptides.txt contains:

RKEKNVQ
IPKKLLQK
QYFHQLEKMNVK
IPKKLLQK
GDLSTALEVAIDCYEK
QYFHQLEKMNVKIPENIYR
RKEKNVQ
VLAKHGKLQDAIN
ILGFMK
LEDVALQILL

推荐答案

一种方法是：

while read p; do
  echo "$p"
done <peptides.txt

As在评论中指出，这具有修剪前导空格，解释反斜杠序列和跳过尾随线的副作用，如果它缺少终止换行符。如果这些是问题，你可以这样做：

As pointed out in the comments, this has the side effects of trimming leading whitespace, interpretting backslash sequences, and skipping the trailing line if it's missing a terminating linefeed. If these are concerns, you can do:

while IFS="" read -r p || [ -n "$p" ]
do
  printf '%s\n' "$p"
done < peptides.txt

---

特殊情况下，如果循环体可能从标准输入读取，您可以打开文件使用不同的文件描述符：

---

Exceptionally, if the loop body may read from standard input, you can open the file using a different file descriptor:

while read -u 10 p; do
  ...
done 10<peptides.txt

这里，10只是一个任意数字（不同于0,1,2）。

Here, 10 is just an arbitrary number (different from 0, 1, 2).

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