You can see the parameter was used as$filename, and read line by line with thewhile read linesyntax from the parameter supplied on the command line. Conclusion In this article, we have discussed how to read lines using the while loop in bash programming. We have implemented different methods...
grep'*foo*'file# Globs in regex contextsfind . -execfoo {} && bar {} \;# Prematurely terminated find -execsudoecho'Var=42'> /etc/profile# Redirecting sudotime --format=%s sleep 10# Passing time(1) flags to time builtinwhilereadh;dossh"$h"uptime# Commands eating while loop inputali...
echo"the variable X is not the empty string" fi 运行这个脚本,输出如下: the variable X is not the empty string 为何?这是因为shell将$X展开为空字符串,表达式[-n]返回真值(因为改表达式没有提供参数)。再看这个脚本: 1 2 3 4 5 #!/bin/bash X="" if[ -n"$X"];then# -n 用来检查变量是...
译:-l的作用是使bash变成一个login shell-r If the -r option is present, the shell becomes restricted (see RESTRICTED SHELL below).-s If the -s option is present, orifno arguments remain after option processing,thencommands are read from the standard input. This option allows the positional ...
In Bash, you must use a read-while loop or the mapfile builtin command to safely parse the line of a file. A read-while loop is a while loop using the read command with the -r option. You should never use a for loop with other commands, like cat or ls, as it would lead to ...
array+=("$line")the line variable stores the value of each line in the file and using this argument, it gets stored in an array. done < "$file"instructs the loop to read the filename from the$fileusing the input redirection<. ...
while read VAR; do BODYdone < /PATH/FROM/SOMEFILE 1. 2. 示例:打印UID为偶数的用户的名称、UID和默认shell。 #!/bin/bashwhile read line; do userName=$(echo $line | cut -d : -f 1) userID=$(echo $line | cut -d : -f 3) ...
The easiest and safest way to read a file into a bash array is to use the mapfile builtin which read lines from the standard input. When no array variable name is provided to the mapfile command, the input will be stored into the $MAPFILE variable. Note that the mapfile command will...
# Usage: lines_loop "file" count=0 while IFS= read -r _; do ((count++)) done < "$1" printf '%s\n' "$count" } 用法示例: $ lines ~/.bashrc 48 $ lines_loop ~/.bashrc 48 计算目录中的文件或目录 这是通过将glob的输出传递给函数然后计算参数的数量来实现的。
--init-file file --rcfile file Execute commands from file instead of the standard per- sonal initialization file ~/.bashrc if the shell is interactive (see INVOCATION below). --login Equivalent to -l. --noediting Do not use the GNU readline library to read command lines when the shell ...