sed用变量替换 [英] sed replace with variable

问题描述

我想用正确的计算值(以给定角度的弧度，即变量n1)替换表示 alpha = -pi/...的行

I want to replace a line that says alpha = -pi/... with the correct calculated value in radians of the angle given ie variable n1

#!/bin/bash

read -p "Angle in degrees : " n1

## Convert angle to radians

printf -v "n2" "%.0f" $(echo | bc | awk "BEGIN {print 180/$n1}")

echo "$n1 Degrees = pi/$n2"

printf -v "n3" "alpha = -pi/$n2;"

echo "${n3}"

cd /home/src/octave_scripts/makemesh_rot


sed  "s/alpha =.*/$n3/" makemesh_rot.m > makemesh_rot.m_temp

我环顾四周，尝试了几种变体，将"s/alpha =.*/$ n3/" 更改为's/alpha =.*/"$ n3"/和其他几种方法，就是用 $ n3

Ive had a look around and tried a few variations changing "s/alpha =.*/$n3/" to 's/alpha =.*/"$n3"/' and a few other ways all that does is substitues alpha = -pi/... with $n3

推荐答案

我非常定期地执行以下操作:

I do this very regularly as follows:

sed -i -e "s/alpha = .*/alpha = ${n3}/g" makemesh_rot.m

-i 参数直接在原位替换事物，从而使临时文件过时.

The -i parameter replaces things directly in-place, which renders the temporary file obsolete.

这篇关于sed用变量替换的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！