# test ##### 字串或文字的比對 ``` Str1 = str2 | 當str1與str2相同時, 傳回True Str1 != str2| 當str1與str2不同時, 傳回True Str1 < Str2 Str1 <= Str2 Str1 > Str2 Str1 >= Str2 Str | 當str不是空字符時, 傳回True -n str | 當str的長度大於0時, 傳回True -z str | 當str的長度是0時, 傳回True ``` ##### \[ \]與\[\[ \]\] 差別 - `[ ... ]` : POSIX 相容指令，別名 test，用於條件判斷式。 - `[[ ... ]]` : Bash 專有語法，可用於更複雜的條件判斷式。 - `[ -n "$VAR_STR"]` : 使用 \[ \] 時要注意變數的雙引號用法。範例： ```bash VAR_STR="" if [[ -n $VAR_STR ]]; then echo "var str is nonzero with [[" else echo "var str is zero with [[" fi if [ -n $VAR_STR ]; then echo "var str is nonzero with [" else echo "var str is zero with [" fi ``` Output: ``` var str is zero with [[ var str is nonzero with [ ``` Fix: ```bash VAR_STR="" if [[ -n $VAR_STR ]]; then echo "var str is nonzero with [[" else echo "var str is zero with [[" fi if [ -n "$VAR_STR" ]; then # <<<< echo "var str is nonzero with [" else echo "var str is zero with [" fi ``` ##### 數值型比對整數 ``` Int1 -eq int2 |當int1等於int2時, 傳回True Int1 -ge int2 |當int1大於/等於int2時, 傳回True Int1 -le int2 |當int1小於/等於int2時, 傳回True Int1 -gt int2 |當int1大於int2時, 傳回True Int1 -ne int2 |當int1不等於int2時, 傳回True Int1 -lt int2 |當int1小於 int2時, 傳回True ``` 浮點數 ```bash asr=87.22 thre=90.00 if (( $(echo "$asr < $thre" | bc -l) )); then return 0 # true fi ``` ##### 檔案的比對 ``` -e file | 檔案是否存在 -d file | 當file是一個目錄時, 傳回 True -f file | 當file是一個普通檔案時, 傳回 True -r file | 當file是一個可讀檔案時, 傳回 True -s file | 當file檔案內容長度大於0時, 傳回 True; 空白內容傳回 False -w file | 當file是一個可寫檔案時, 傳回 True -x file | 當file是一個可執行檔案時, 傳回 True ``` File operators list

Operator	Returns
`-a FILE`	True if file exists.
`-b FILE`	True if file is block special.
`-c FILE`	True if file is character special.
`-d FILE`	True if file is a directory.
`-e FILE`	True if file exists.
`-f FILE`	True if file exists and is a regular file.
`-g FILE`	True if file is set-group-id.
`-h FILE`	True if file is a symbolic link.
`-L FILE`	True if file is a symbolic link.
`-k FILE`	True if file has its `sticky' bit set.
`-p FILE`	True if file is a named pipe.
`-r FILE`	True if file is readable by you.
`-s FILE`	True if file exists and is not empty.
`-S FILE`	True if file is a socket.
`-t FD`	True if FD is opened on a terminal.
`-u FILE`	True if the file is set-user-id.
`-w FILE`	True if the file is writable by you.
`-x FILE`	True if the file is executable by you.
`-O FILE`	True if the file is effectively owned by you.
`-G FILE`	True if the file is effectively owned by your group.
`-N FILE`	True if the file has been modified since it was last read.
`! EXPR`	Logical not.
`EXPR1 && EXPR2`	Perform the `and` operation.
`EXPR1 \|\| EXPR2`	Perform the `or` operation.

##### 布林變數應用 ```shell # Let us Declare Two Boolean Variables # Set this one to true jobstatus=true # Check it if [ "$jobstatus" = true ] ; then echo 'Okay :)' else echo 'Noop :(' fi # Double bracket format syntax to test Boolean variables in bash bool=false if [[ "$bool" = true ]] ; then echo 'Done.' else echo 'Failed.' fi ``` ##### 更多範例 ```shell # 如果前個指令執行有錯誤時，會執行兩個程序 [ ! $? -eq 0 ] && echo "Abort the process!! you can try it agian after you made change." && exit 1 # 或者 [ ! $? -eq 0 ] && { echo "Abort the process!! you can try it agian after you made change." exit 1 } # if [[ $RETURN_CODE != 0 ]]; then echo "Zulip first start database initi failed in \"initialize-database\" exit code $RETURN_CODE. Exiting." exit $RETURN_CODE fi # if [[ $TIMEOUT -eq 0 ]]; then echo "Could not connect to database server. Exiting." unset PGPASSWORD exit 1 fi # if (($? > 0)); then echo "$SECRET_KEY = $SECRET_VAR" >> "$DATA_DIR/zulip-secrets.conf" echo "Secret added for \"$SECRET_KEY\"." fi # if test "x$newbranch" = x; then newbranch=`git branch -a | grep "*" | cut -d ' ' -f2` fi # Check router home directory. [ -d "$PROD_HOME" ] || { echo "Router home directory ($PROD_HOME) not found" exit 1 } # AND autoBackupConfiguration() { if ([ "$AUTO_BACKUP_ENABLED" != "True" ] && [ "$AUTO_BACKUP_ENABLED" != "true" ]); then rm -f /etc/cron.d/autobackup echo "Auto backup is disabled. Continuing." return 0 fi } # OR if [ "$MANUAL_CONFIGURATION" = "False" ] || [ "$MANUAL_CONFIGURATION" = "false" ]; then databaseConfiguration secretsConfiguration authenticationBackends zulipConfiguration fi # Die if $f1 or $f2 is missing if [ ! -f "$f1" ] || [ ! -f "$f2" ] then echo "Required files are missing." else echo "Let us build SFTP jail." fi # And if [[ $age -ge 18 ]] && [[ $nat -eq "Indian" ]];then echo "You can vote!!!" else echo "You can not vote" fi # multiple AND if [ -e "$DATA_DIR/.initiated" ] && ([ "$FORCE_FIRST_START_INIT" != "True" ] && [ "$FORCE_FIRST_START_INIT" != "true" ]); then echo "First Start Init not needed. Continuing." return 0 fi # one-liner [[ -z "$var" ]] && echo "NULL" || echo "NOT NULL" # if age is greater than or equal to 18 then the program will print "Adult" or it will print "Minor". [[ $age -ge 18 ]] && echo "Adult" || echo "Minor" # Contain a substring if [[ $var = *pattern1* ]]; then echo "Do something" fi [[ $1 != *cyberciti.biz/faq/* ]] && { printf "Error: Specify faq url (e.g., http://www.cyberciti.biz/faq/url-1-2-3/)\n"; exit 2; } if [[ $fullstring == *"$substr"* ]]; # Regex if [[ $ip =~ ^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}$ ]]; then head="win00000:hascom_command.ksh : hostname:wintstc, monitor port#:17911" if [[ $head =~ ^win00000.*$ ]]; then # Check the the number of the version [ "$(echo "$TMUX_VERSION >= 2.4" | bc)" = 1 ] || echo "The version $TMUX_VERSION is outdated" ``` Two functions (Is\_alert & Notify) return True ```bash if Is_alert && Notify; then echo "Send_mail" fi ```