Posts Tagged ‘read’

Reading a file line by line in Bash

Posted: 26th July 2015 by Tim in Bash, Linux
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There are a few ways to read a file in bash, each with their own caveats. If you’re looking to read a file line-by-line verbatim, including blank lines, then using a simple while loop should do the trick. For example, the following code will print the contents of a file with line numbers: line_no=0 while […]

Pause in Bash

Posted: 27th June 2015 by Tim in Bash, Linux
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Sometimes it is useful to pause a script until the user is ready to proceed. In Windows Batch scripting, this can be done with the PAUSE command. In Bash, the same thing can be done using read with the right parameters: read -rn1 -p “Press any key to continue” This command is doing the following: […]

FIFOs are a very simple tool for communicating between processes. And using them in python is very easy. Simply call os.mkfifo(<path>) and treat the FIFO like any other file. For example, we can create two simple python scripts, one for sending and one for receiving. sender.py import os path = “/tmp/my_program.fifo” os.mkfifo(path) fifo = open(path, […]

Reading from a file in C

Posted: 31st October 2010 by Tim in C
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Reading data from a file is fairly common. The stdio.h provides us with a function, getline, which allows us to read lines from a file without worrying about buffer overflows and other memory corruption issues that C is famous for. The following code opens a file named “myfile.txt” and prints out each line with the […]

Reading from a file in C++

Posted: 27th September 2010 by Tim in C++
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Reading data from a file is common in programming. C++ makes this process fairly painless with the ifstream class. When combined with the string class, you can avoid the memory and buffer overflow issues which you would have to deal with in C. The following example opens a file named “myfile.txt” and prints out each […]