DB2通過bash腳本輸出到變量

Question

我希望有人可以幫助將db2命令的輸出應用於一個變量，以便稍後在腳本中使用。

到目前爲止，我在...

db2 "connect to <database> user <username> using <password>" 

while read HowMany ; 
do 
    Counter=$HowMany 
    echo $HowMany 
done < <(db2 -x "SELECT COUNT(1) FROM SYSCAT.COLUMNS WHERE TABNAME = 'TableA' AND TABSCHEMA='SchemaA' AND GENERATED = 'A'") 

當試圖引用$Counter外while循環，它返回SQL1024N A database connection does not exist. SQLSTATE=08003一樣的echo $HowMany

我試着用管的另一種方法，這使得$HowMany顯示正確的值，但是因爲這是一個子外殼，所以它隨後會丟失。

我寧可不使用臨時文件，如果可能的話刪除它們，因爲如果腳本隨時中止，我不喜歡留下文件。

Answer 1

在Linux和UNIX的DB2 CLP可以處理command substitution不失其數據庫連接上下文，從而能夠將查詢結果捕獲到本地shell變量或將其視爲內聯塊文本。

#!/bin/sh 
# This script assumes the db2profile script has already been sourced 

db2 "connect to <database> user <username> using <password>" 

# Backtick command substitution is permitted 
HowMany=`db2 -x "SELECT COUNT(1) FROM SYSCAT.COLUMNS WHERE TABNAME = 'TableA' AND TABSCHEMA='SchemaA' AND GENERATED = 'A'"` 

# This command substitution syntax will also work 
Copy2=$(db2 -x "SELECT COUNT(1) FROM SYSCAT.COLUMNS WHERE TABNAME = 'TableA' AND TABSCHEMA='SchemaA' AND GENERATED = 'A'") 

# One way to get rid of leading spaces 
Counter=`echo $HowMany` 

# A while loop that is fed by process substitution cannot use 
# the current DB2 connection context, but combining a here 
# document with command substitution will work 
while read HowMany ; 
do 
    Counter=$HowMany 
    echo $HowMany 
done <<EOT 
$(db2 -x "SELECT COUNT(1) FROM SYSCAT.COLUMNS WHERE TABNAME = 'TableA' AND TABSCHEMA='SchemaA' AND GENERATED = 'A'") 
EOT 

Answer 2

正如您發現的，一個shell中的DB2連接不可用於子shell。你可以使用一個子shell，但你必須將CONNECT語句放在該子shell中。

所以它更像是一個簡單的重寫的，並且不使用一個子shell：

db2 "connect to <database> user <username> using <password>" 

db2 -x "SELECT COUNT(1) FROM SYSCAT.COLUMNS WHERE TABNAME = 'TableA' AND TABSCHEMA='SchemaA' AND GENERATED = 'A'" | while read HowMany ; do 
    Counter=$HowMany 
    echo $HowMany 
done