What is a pipe and give an example?

Unix Interview Questions

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102. What is a pipe and give an example?

A pipe is two or more commands separated by pipe char '|'. That tells the shell to arrange for the output of the preceding command to be passed as input to the following command.
Example : ls -l | pr
The output for a command ls is the standard input of pr.
When a sequence of commands are combined using pipe, then it is called pipeline.

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Other Interview Questions

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• Brief about the directory representation in UNIX
• What are the Unix system calls for I/O?
• How do you change File Access Permissions?
• What are links and symbolic links in UNIX file system?
• What is a FIFO?
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• Discuss the mount and unmount system calls
• How does the inode map to data block of a file?
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• What are various IDs associated with a process?
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• Predict the output of the following program code
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• What Happens when you execute a program?
• What Happens when you execute a command?
• What is a Daemon?
• What is 'ps' command for?
• How would you kill a process?
• What is an advantage of executing a process in background?
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• What is major difference between the Historic Unix and the new BSD release of Unix System V in terms of Memory Management?
• What is the main goal of the Memory Management?
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• What are the criteria for choosing a process for swapping out of the memory to the swap device?
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• Difference between the fork() and vfork() system call?
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• In what way the Fault Handlers and the Interrupt handlers are different?
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• What does the swapping system do if it identifies the illegal page for swapping?
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• 74. What is ex and vi ?
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