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scripting:processtree [2019/08/30 14:45]
ersen [The process tree]
scripting:processtree [2019/08/30 14:55] (current)
ersen [Bash playing with pipes]
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 </​code>​ </​code>​
  
-Note once again, ''​ls''​ can't influence the ''​grep''​ environment''​grep''​ can't influence the ''​ls'' ​environmet, and neither ''​grep''​ nor ''​ls''​ can influence the ''​bash''​ environment.+Note once again, ''​ls''​ can't influence the ''​grep''​ environment''​grep''​ can't influence the ''​ls'' ​environment, and neither ''​grep''​ nor ''​ls''​ can influence the ''​bash''​ environment.
  
 __**How is that related to shell programming?​!?​**__ __**How is that related to shell programming?​!?​**__
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 </​code>​ </​code>​
  
-See the relationship?​ The forked Bash process will count the lines like a charm. It will also set the variable ''​counter''​ as directed. But if everything ends, this extra process will be terminated - **your "​counter"​ variable is gone** You see a 0 because in the main shell it was 0, and wasn't changed by the child process!+See the relationship?​ The forked Bash process will count the lines like a charm. It will also set the variable ''​counter''​ as directed. But if everything ends, this extra process will be terminated - **your "​counter"​ variable is gone.** You see a 0 because in the main shell it was 0, and wasn't changed by the child process!
  
 __**So, how do we count the lines?**__ __**So, how do we count the lines?**__
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 </​code>​ </​code>​
  
-It's nearly self-explanitory. The ''​while''​ loop runs in the **current shell**, the counter is incremented in the **current shell**, everything vital happens in the **current shell**, also the ''​read''​ command sets the variable ''​REPLY''​ (the default if nothing is given), though we don't use it here. +It's nearly self-explanatory. The ''​while''​ loop runs in the **current shell**, the counter is incremented in the **current shell**, everything vital happens in the **current shell**, also the ''​read''​ command sets the variable ''​REPLY''​ (the default if nothing is given), though we don't use it here.
 ===== Actions that create a subshell ===== ===== Actions that create a subshell =====
  
  • scripting/processtree.txt
  • Last modified: 2019/08/30 14:55
  • by ersen