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Bash

Date

DATE=$(date +%Y%m%d_%H%M%S)
FILE="/backup/backup-$DATE"

Loop

for OUTPUT in $(Linux-Or-Unix-Command-Here)
do
    command1 on $OUTPUT
    command2 on $OUTPUT
    commandN
done

ref: https://www.cyberciti.biz/faq/bash-for-loop/

Varaible

設定/刪除

export A_VARIBALE
unset A_VARIBALE

使用預設值

ACTOR=${ACTOR:-$GITHUB_ACTOR}
qq=ops:default
echo ${qq#*:}
# default
echo ${qq%:*}
# ops

Return error code when a variable is not found

ref: https://stackoverflow.com/a/307735/3854890

sh-3.2$ STATE=abc
sh-3.2$ : ${STATE:?"Need to set STATE"}
sh-3.2$ echo $?
0
sh-3.2$ unset STATE
sh-3.2$ : ${STATE:?"Need to set STATE"}
sh: STATE: Need to set STATE
sh-3.2$ echo $?
1

Echo Bash List with comma(,)

ROLE_PERMISSIONS=(
    compute.disks.get
    compute.disks.create
    compute.disks.createSnapshot
    compute.snapshots.get
    compute.snapshots.create
    compute.snapshots.useReadOnly
    compute.snapshots.delete
    compute.zones.get
)

echo "$(IFS=","; echo "${ROLE_PERMISSIONS[*]}")"

暫時進到某個 folder 執行指令,不改變目前 path

(cd src/ && git checkout $NEW_VERSION_SHA)

ANSI - 輸出文字變色

https://misc.flogisoft.com/bash/tip_colors_and_formatting

echo -e "Default \e[31mRed"
echo -e "\e[31mHello\e[0m World"
echo -e "\e[1;31mHello\e[0m World"
-e: to use \e[31m

Reference


Last update: December 3, 2020

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