我怎么用echo来做呢?
perl -E 'say "=" x 100'
我怎么用echo来做呢?
perl -E 'say "=" x 100'
当前回答
function repeatString()
{
local -r string="${1}"
local -r numberToRepeat="${2}"
if [[ "${string}" != '' && "${numberToRepeat}" =~ ^[1-9][0-9]*$ ]]
then
local -r result="$(printf "%${numberToRepeat}s")"
echo -e "${result// /${string}}"
fi
}
样本运行
$ repeatString 'a1' 10
a1a1a1a1a1a1a1a1a1a1
$ repeatString 'a1' 0
$ repeatString '' 10
参考库:https://github.com/gdbtek/linux-cookbooks/blob/master/libraries/util.bash
其他回答
如果你想重复一个字符n次,n是一个变量的次数,这取决于,比如说,字符串的长度,你可以这样做:
#!/bin/bash
vari='AB'
n=$(expr 10 - length $vari)
echo 'vari equals.............................: '$vari
echo 'Up to 10 positions I must fill with.....: '$n' equal signs'
echo $vari$(perl -E 'say "=" x '$n)
它显示:
vari equals.............................: AB
Up to 10 positions I must fill with.....: 8 equal signs
AB========
printf -- '=%.0s' {1..100}
双破折号——表示“命令行标志的结束”,所以不要试图解析命令行选项后面的内容。
如果你想打印破折号字符,而不是=字符,多次,不包括双破折号-这是你会得到的:
$ printf '-%.0s' {1..100}
bash: printf: -%: invalid option
printf: usage: printf [-v var] format [arguments]
为什么不创建这样的一行函数呢:
function repeat() { num="${2:-100}"; printf -- "$1%.0s" $(seq 1 $num); }
然后,你可以这样调用它:
$ repeat -
----------------------------------------------------------------------------------------------------
或者像这样:
$ repeat =
====================================================================================================
或者像这样:
$ repeat '*' 8
********
没有简单的方法。但是举个例子:
seq -s= 100|tr -d '[:digit:]'
# Editor's note: This requires BSD seq, and breaks with GNU seq (see comments)
或者是一种符合标准的方式:
printf %100s |tr " " "="
还有一个tput代表,但对于我手头的终端(xterm和linux),它们似乎不支持它:)
如果你想在echo和printf的不同实现之间遵循posix并保持一致性,和/或shell而不仅仅是bash:
seq(){ n=$1; while [ $n -le $2 ]; do echo $n; n=$((n+1)); done ;} # If you don't have it.
echo $(for each in $(seq 1 100); do printf "="; done)
...将在所有地方产生与perl -E 'say "=" x 100'相同的输出。
我的答案有点复杂,可能并不完美,但对于那些希望输出大数字的人来说,我能够在3秒内完成大约1000万。
repeatString(){
# argument 1: The string to print
# argument 2: The number of times to print
stringToPrint=$1
length=$2
# Find the largest integer value of x in 2^x=(number of times to repeat) using logarithms
power=`echo "l(${length})/l(2)" | bc -l`
power=`echo "scale=0; ${power}/1" | bc`
# Get the difference between the length and 2^x
diff=`echo "${length} - 2^${power}" | bc`
# Double the string length to the power of x
for i in `seq "${power}"`; do
stringToPrint="${stringToPrint}${stringToPrint}"
done
#Since we know that the string is now at least bigger than half the total, grab however many more we need and add it to the string.
stringToPrint="${stringToPrint}${stringToPrint:0:${diff}}"
echo ${stringToPrint}
}