bash 中的逻辑表达式

发布于 2024-11-04 22:26:51 字数 849 浏览 0 评论 0原文

该脚本的目的是检查包含目录名称列表的文件，并将其附加到不存在的其他文件目录名称中。

#!/bin/bash
FILES="list.txt"
2nd_file="2nd_list.txt"
for f in $FILES
do
    # if  backup dir exists, read next dir
if [ /bin/grep -q $f $2nd_file ]
then
    echo "Skiping $f file..."
    continue  # read next file
fi
    # we are hear means no file exists
    echo "$f" >>$2nd_file
done

我在 if 表达式中收到错误。

我理解你的答案并更改了脚本：

 #!/bin/bash
 FILES="list.txt"
 2nd_file="2nd_list.txt"
 for f in $FILES
 do
        # if  backup dir exists, read next dir
 /bin/grep -q $f $2nd_file
 if [ $? -eq 0 ]
 then
    echo "Skiping $f file..."
    continue  # read next file
fi
    # we are hear means no dir exists
     echo "$f" >>$2nd_file
done

但现在脚本不从文件

输出读取目录名称的一个小问题是：

 Skiping list.txt file...

原文

The purpose of the script is go over file contains list of directory names and append to other file directory names that are not exist in.

#!/bin/bash
FILES="list.txt"
2nd_file="2nd_list.txt"
for f in $FILES
do
    # if  backup dir exists, read next dir
if [ /bin/grep -q $f $2nd_file ]
then
    echo "Skiping $f file..."
    continue  # read next file
fi
    # we are hear means no file exists
    echo "$f" >>$2nd_file
done

I getting errors in if expression.

I understood what your answers about and changed the script :

 #!/bin/bash
 FILES="list.txt"
 2nd_file="2nd_list.txt"
 for f in $FILES
 do
        # if  backup dir exists, read next dir
 /bin/grep -q $f $2nd_file
 if [ $? -eq 0 ]
 then
    echo "Skiping $f file..."
    continue  # read next file
fi
    # we are hear means no dir exists
     echo "$f" >>$2nd_file
done

But now a small problem that script doesn't read directory names from FILES

Output is :

 Skiping list.txt file...

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他夏了夏天 2024-11-11 22:26:51

你的 if 表达式应该是：

if  /bin/grep -q $f $2nd_file

不带方括号

编辑帖子时已编辑：

你的脚本应该是：

#!/bin/bash
FILES="list.txt"
2nd_file="2nd_list.txt"
for f in $(cat $FILES) # see the modification
do
    # if  backup dir exists, read next dir
if /bin/grep -q $f $2nd_file # see the modification
then
    echo "Skiping $f file..."
    continue  # read next file
fi
    # we are hear means no file exists
    echo "$f" >>$2nd_file
done

我所做的修改是：

在“for”中：你需要的内容$FILE 存档，而不是字符串“list.txt”（$FILES 变量的值），因此您必须使用 cat 或“<”转储这些内容（即：while read f; do ... ; did <$FILES）
在 if 语句中：您必须评估命令。命令是 grep 。如果 grep 返回 0 那么你的“if”工作就完成了；任何其他返回值将跳过您的 if 语句。（这就像对返回状态进行无用的检查，但效率更高）

your if expression should be:

if  /bin/grep -q $f $2nd_file

without square brackets

EDITED as you edited your post:

Your script should be:

#!/bin/bash
FILES="list.txt"
2nd_file="2nd_list.txt"
for f in $(cat $FILES) # see the modification
do
    # if  backup dir exists, read next dir
if /bin/grep -q $f $2nd_file # see the modification
then
    echo "Skiping $f file..."
    continue  # read next file
fi
    # we are hear means no file exists
    echo "$f" >>$2nd_file
done

The modifications I've made are:

in the "for": you need the content of $FILE archive, not the string "list.txt" (the value of $FILES variable) so you have to dump those contents with cat or with a "<" (ie: while read f; do ... ; done < $FILES)
in the if statement: you have to evaluate a command. The command is you grep. If grep returns 0 then your "if" stuff will be done; any other return value will skip your if statement. (that's like your useless check of the return status but more efficient)

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