注意:

以下是本主题中其他答案的浓缩和组织，尤其是Stefan Lasiewski和Serge Stroobandt的优秀作品 Lasiewski和我推荐高级bash脚本编写指南中的Ch 19 (Here Documents)

问题(如何在bash脚本中将here文档(又名heredoc)写入文件?)有(至少)3个主要的独立维度或子问题:

要覆盖现有文件、追加到现有文件还是写入新文件? 您的用户或其他用户(例如root)拥有该文件吗? 您是想按字面意思写heredoc的内容，还是让bash在heredoc内解释变量引用?

(还有其他我认为不重要的方面/子问题。考虑编辑这个答案来添加它们!)下面是上面列出的问题的一些更重要的维度组合，使用各种不同的分隔标识符——关于EOF没有什么神圣的，只要确保你用作分隔标识符的字符串没有出现在你的heredoc中:

To overwrite an existing file (or write to a new file) that you own, substituting variable references inside the heredoc: cat << EOF > /path/to/your/file This line will write to the file. ${THIS} will also write to the file, with the variable contents substituted. EOF To append an existing file (or write to a new file) that you own, substituting variable references inside the heredoc: cat << FOE >> /path/to/your/file This line will write to the file. ${THIS} will also write to the file, with the variable contents substituted. FOE To overwrite an existing file (or write to a new file) that you own, with the literal contents of the heredoc: cat << 'END_OF_FILE' > /path/to/your/file This line will write to the file. ${THIS} will also write to the file, without the variable contents substituted. END_OF_FILE To append an existing file (or write to a new file) that you own, with the literal contents of the heredoc: cat << 'eof' >> /path/to/your/file This line will write to the file. ${THIS} will also write to the file, without the variable contents substituted. eof To overwrite an existing file (or write to a new file) owned by root, substituting variable references inside the heredoc: cat << until_it_ends | sudo tee /path/to/your/file This line will write to the file. ${THIS} will also write to the file, with the variable contents substituted. until_it_ends To append an existing file (or write to a new file) owned by user=foo, with the literal contents of the heredoc: cat << 'Screw_you_Foo' | sudo -u foo tee -a /path/to/your/file This line will write to the file. ${THIS} will also write to the file, without the variable contents substituted. Screw_you_Foo

例如，你可以使用它:

首先(进行ssh连接):

while read pass port user ip files directs; do
    sshpass -p$pass scp -o 'StrictHostKeyChecking no' -P $port $files $user@$ip:$directs
done <<____HERE
    PASS    PORT    USER    IP    FILES    DIRECTS
      .      .       .       .      .         .
      .      .       .       .      .         .
      .      .       .       .      .         .
    PASS    PORT    USER    IP    FILES    DIRECTS
____HERE

第二个(executing的聚会):

while read pass port user ip; do
    sshpass -p$pass ssh -p $port $user@$ip <<ENDSSH1
    COMMAND 1
    .
    .
    .
    COMMAND n
ENDSSH1
done <<____HERE
    PASS    PORT    USER    IP
      .      .       .       .
      .      .       .       .
      .      .       .       .
    PASS    PORT    USER    IP    
____HERE

第三(执行命令):

Script=$'
#Your commands
'

while read pass port user ip; do
    sshpass -p$pass ssh -o 'StrictHostKeyChecking no' -p $port $user@$ip "$Script"

done <<___HERE
PASS    PORT    USER    IP
  .      .       .       .
  .      .       .       .
  .      .       .       .
PASS    PORT    USER    IP  
___HERE

(使用变量)。

while read pass port user ip fileoutput; do
    sshpass -p$pass ssh -o 'StrictHostKeyChecking no' -p $port $user@$ip fileinput=$fileinput 'bash -s'<<ENDSSH1
    #Your command > $fileinput
    #Your command > $fileinput
ENDSSH1
done <<____HERE
    PASS    PORT    USER    IP      FILE-OUTPUT
      .      .       .       .          .
      .      .       .       .          .
      .      .       .       .          .
    PASS    PORT    USER    IP      FILE-OUTPUT
____HERE

使用tee代替cat和I/O重定向可能会有用:

tee newfile <<EOF
line 1
line 2
line 3
EOF

它更简洁，而且与重定向操作符不同，如果您需要以根权限写入文件，它可以与sudo结合使用。

对于那些寻找纯bash解决方案(或需要速度)的人来说，这里有一个简单的解决方案，没有cat:

# here-doc tab indented
{ read -r -d '' || printf >file '%s' "$REPLY"; } <<-EOF
        foo bar
EOF

或简单的“mycat”函数(并避免在环境中留下REPLY):

mycat() {
  local REPLY
  read -r -d '' || printf '%s' "$REPLY"
}
mycat >file <<-EOF
        foo bar
EOF

快速比较“mycat”vs OS cat(1000循环>/dev/null在我的OSX笔记本电脑上):

mycat:
real    0m1.507s
user    0m0.108s
sys     0m0.488s

OS cat:
real    0m4.082s
user    0m0.716s
sys     0m1.808s

注意:mycat不处理文件参数，它只处理“将heredoc写入文件”的问题。

当需要root权限时

当目标文件需要root权限时，使用|sudo tee而不是>:

cat << 'EOF' |sudo tee /tmp/yourprotectedfilehere
The variable $FOO will *not* be interpreted.
EOF

cat << "EOF" |sudo tee /tmp/yourprotectedfilehere
The variable $FOO *will* be interpreted.
EOF

阅读高级bash脚本编写指南第19章。这里的文档。

下面是一个将内容写入/tmp/yourfilehere文件的示例

cat << EOF > /tmp/yourfilehere
These contents will be written to the file.
        This line is indented.
EOF

注意，最后的'EOF'(限制字符串)在单词前面不应该有任何空白，因为这意味着限制字符串将不会被识别。

在shell脚本中，您可能希望使用缩进来使代码可读，但这可能会产生对here文档中的文本缩进的不良影响。在这种情况下，使用<<-(后面跟着破折号)禁用开头的制表符(注意，为了测试这一点，您需要用制表符替换开头的空白，因为我不能在这里打印实际的制表符)。

#!/usr/bin/env bash

if true ; then
    cat <<- EOF > /tmp/yourfilehere
    The leading tab is ignored.
    EOF
fi

如果你不想解释文本中的变量，那么使用单引号:

cat << 'EOF' > /tmp/yourfilehere
The variable $FOO will not be interpreted.
EOF

通过命令管道来管道heredoc:

cat <<'EOF' |  sed 's/a/b/'
foo
bar
baz
EOF

输出:

foo
bbr
bbz

．.． 或者使用sudo将heredoc写入文件:

cat <<'EOF' |  sed 's/a/b/' | sudo tee /etc/config_file.conf
foo
bar
baz
EOF