在Bash中,while read循环用于从输入流中逐行读取数据,并将每一行赋值给一个变量,然后执行循环体中的命令。串联Bash问题是指在while read循环中如何实现多个命令的串联执行。 要在while read循环中实现多个命令的串联执行,可以使用管道符号|将命令连接起来。管道符号将前一个命令的输出作为后一个命令的输入。 以下是一...
linux bash while read循环读管道 在Linux的Bash中，可以使用`while read`循环从管道中读取数据。下面是一个示例脚本：```bash #!/bin/bash sum=0 cat ./whileTest.txt | while read line do line_n=`echo $line|sed 's/(^0-9)//g'`if ( "$line_n" != '' )then echo $line_n sum=$($...
使用'while read'使用bash遍历列表是一种在Bash脚本中遍历列表的常见方法。它可以逐行读取输入,并将每行的内容赋值给一个变量,然后可以在循环体中对该变量进行处理。 以下是使用'while read'遍历列表的示例代码: 代码语言:bash 复制 #!/bin/bash# 列表文件的路径list_file="list.txt"# 使用'while read'遍历列表...
Using passing file name from a command In a bash file, you need to add the following code script. In this script, we have to take a filename as an argument. First, the value of an argument is read by a$1variable which has a filename for reading. It will check that filename exist...
偶遇bash 的while read line 的问题 自己开发的过程中,我从数据库里读出来一个值,写入某个临时文件,再让脚本做 cat tmp.log |while read line 的时候 readline每次都是少一行, 最后发现,是换行符的问题 从数据库读出的是纯字符,没有换行,需要手动添加一个"\n" 问题解决...
bash shell if-statement while-loop m3u 我正在编写一个脚本来解析m3u文件。目标是检索变量标记和url。我用这个文件做了测试。 #!/bin/bash echo "name,tvg-id,tvg-name,tvg-country,group-title,languages,url" while IFS= read -r line; do tags_detect="$(echo "$line" | grep -Eo '^#EXTINF:')...
while read LINE do COMMAND done < FILE The same construction in one line (easy to use on the Linux command line): while read LINE; do COMMAND; done < FILE As example lets print all users from the/etc/passwdfile: $ while read LINE; do echo "$LINE" | cut -f1 -d":"; done < ...
i'm reading a few variables from a file using while read a b c; do (something) done < filename is there an elegant way to skip a variable (read in an empty value), i.e. if I want a=1 b= c=3, what should I write in the file?
read -p "Input something:" STRING done # 方法一: #!/bin/bash # who | grep "hadoop" &> /dev/null RETVAL=$? until [ $RETVAL -eq 0 ];do echo "hadoop is not logged in." sleep 5 who | grep "hadoop" &> /dev/null RETVAL=$? done echo "hadoop is logged in." # 方法二: ...
while read VARIABLE do code done Piping in Linux Normally we will use thecat commandto view the contents of the file from the terminal. Also, we will pipe the output of thecat commandto other commands likegrep,sort, etc. Similarly, we will use thecat commandhere to read the content of...