Linux echo 換行 All In One

本文轉載自查看原文 2021-10-13 15:35 354 2>&1/ cron/ \n/ Linux/ 換行/ crontab/ echo/ 多行注釋/ EOF/ bash shell

Linux echo 換行 All In One

auto-install-npm.sh

#!/bin/sh

# sh/zsh/bash 選擇默認

# echo "🚀 linux shell 定時器" && npm i -g app-node-env
# echo "🚀 linux shell 定時器" && yarn global add app-node-env

# 寫入 logs
echo "🚀 linux shell 定時器" >> ./auto-install-npm.log 2>&1

# echo 換行
# echo -e "\n\n\n"
# echo "\n"

# 安裝 log
# yarn global add app-node-env >> ./auto-install-npm.log 2>&1

# 安裝不需要 log
yarn global add app-node-env

# Linux Bash shell 腳本定時器 All In One
# https://www.cnblogs.com/xgqfrms/p/15384401.html

zsh bug ???

# ❌
➜  ~ sudo ./auto-install-npm.sh >> /var/log/auto-install-npm.log 2>&1
zsh: permission denied: /var/log/auto-install-npm.log
➜  ~ ./auto-install-npm.sh >> /var/log/auto-install-npm.log 2>&1 
zsh: permission denied: /var/log/auto-install-npm.log

# ✅ OK
$ ./auto-install-npm.sh >> ./auto-install-npm.log 2>&1

linux `2>&1`

cron logs

https://stackoverflow.com/questions/4811738/how-to-log-cron-jobs

# 2>&1, 標准輸出和錯誤輸出二合一

* * * * * ./auto-install-npm.sh >> /var/log/auto-install-npm.log 2>&1

https://stackoverflow.com/questions/818255/in-the-shell-what-does-21-mean

crontab / corn


# 定時器任務test
# 每隔 30 分鍾運行一次，使用 sh 自動安裝 app-node-env
# 30 * * * * sh ./auto-install-npm.sh
30 * * * * /bin/sh ./auto-install-npm.sh

https://www.cnblogs.com/xgqfrms/p/15384401.html

echo `\n` 換行 & EOF 多行注釋 All In One


#!/bin/bash

# echo \n ❌
# echo "sed test\n"

# echo -e \n ✅
echo -e "sed test\n"

# echo $"雙引號 ❌"
# echo $"sed test\n"

# echo $'單引號 ✅'
echo $'sed test\n'

printf "sed test\nabc xyz\n\n"

printf "sed test\nabc xyz"
# sed test
# abc xyz%
# printf % bug ❓zsh bug

# multi lines comments `<<EOF` & `EOF`

# multi_lines_comments = <<EOF

<<EOF

The \`%\` is not printed by \`printf\`, it's printed by \`zsh\` as part of its command prompt.

Bash uses \`$\` or something more complicated instead, that's why it looks different with bash.

\`printf\` prints the same thing both times, and following that the shell prints it's command prompt.

This command prompt looks different in \`zsh\` than in \`bash/sh\`.

https://stackoverflow.com/questions/8467424/echo-newline-in-bash-prints-literal-n

EOF

# echo "$multi_lines_comments"