For each iteration of thewhile loop, the read command reads that particular line of the file and assigns it to the bash shell variable $line. The loop runs till the number of lines in the file. After reading the
line done 使用while循环 while read -r line do echo $line done < filename While循环中read命令从标准输入中读取一行,并将内容保存到变量...line中。...在这里,-r选项保证读入的内容是原始的内容,意味着反斜杠转义的行为不会发生。输入重定向...
...tcsh 的语法与 Bash 类似,但是它更为严格。例如在下面的例子中,不要在你的终端的第 2、3 行键入 foreach? 。它只是提示你仍处在构建循环的过程中。...因此你不能像 Bash 或者其他类似的 shell 一样只使用一行命令创建一个 for 循环。 1.7K10...
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As example lets print all users from the/etc/passwdfile: $ while read LINE; do echo "$LINE" | cut -f1 -d":"; done < /etc/passwd root daemon bin [...] TheLINEin this construction – is the name of a variable that stores the line during each loop iteration. ...
Let’s create a 3×3 2D array using nested while loop in Bash: #!/bin/bash i=1 while [ $i -le 3 ] do j=1 while [ $j -le 3 ] do echo "Row: $i Column: $j" ((j++)) done ((i++)) done Reading File Line by Line with Bash while Loop ...
1. Using for ... in statement 2. Using for ((exp1, exp2, exp3)) statement The result will be: Why you can use a bash for loop in one line If you use bash on the command line, this will not guarantee that for loops are inserted into the script. In order to prevent this, it...
line_count=$((line_count + 1)): It will increase the value of theline_countvariable each time the loop iterates. < "$filename": It instructs the loop to use the file stored in the$filenamevariable. And if you were to use the same script, you can expect the following: ...
Bash For Loop In One Line with Files # for i in *; do echo "Found the following file: $i"; done # for i in `cat filelist.txt`; do echo ${i}; done; if a line may include spaces better use a while loop: # cat filelist.txt | while read LINE; do echo "${LINE}"; done ...
Be sure to specify different variable names for each loop. To copy the list of files file1.txt, file2.txt, and file3.txt to the web servers, use this nested loop: $ for i in file{1..3};do for x in web{0..3};do echo "Copying $i to server $x"; scp $i $x; done; ...