Bash redirect stdout dev null

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Question feed. Stack Overflow works best with JavaScript enabled. We see that the result is the same as passing a single filename argument. This is not particularly useful compared to passing a filename argument, but it serves to demonstrate using a file as a source of standard input. Other commands make better use of standard input. The ability of commands to read data from standard input and send to standard output is utilized by a shell feature called pipelines.

Using the pipe operator vertical bar , the standard output of one command can be piped into the standard input of another. We can use less to display, page by page, the output of any command that sends its results to standard output:. This is extremely handy! Using this technique, we can conveniently examine the output of any command that produces standard output. Pipelines are often used to perform complex operations on data. It is possible to put several commands together into a pipeline.

Frequently, the commands used this way are referred to as filters. Filters take input, change it somehow, and then output it. The first one we will try is sort. By including sort in our pipeline, we changed the data to produce a single, sorted list.

The uniq command is often used in conjunction with sort. In this example, we use uniq to remove any duplicates from the output of the sort command. If we want to see the list of duplicates instead, we add the -d option to uniq like so:.

The wc word count command is used to display the number of lines, words, and bytes contained in files. For example:. In this case it prints out three numbers: lines, words, and bytes contained in ls-output. Like our previous commands, if executed without command-line arguments, wc accepts standard input. The -l option limits its output to only report lines. Adding it to a pipeline is a handy way to count things.

To see the number of items we have in our sorted list, we can do this:. The patterns that grep can match can be very complex, but for now we will concentrate on simple text matches.

Such a search might give us an idea of which programs on our system have something to do with file compression. Show activity on this post. Cron used the Bourne shell sh rather than Bash.

Improve this answer. Follow this answer to receive notifications. For example, with the default settings, a NULL is written as an unquoted empty string, while an empty string data value is written with double quotes "". Reading values follows similar rules. Although I suspect something very similar has been asked already Posted: 3 days ago We will show you a little function that you can use to selectively turn off this output and other PSSE output or redirect it to a log file.

This blog post is in response to a question by chip on the python for power systems engineers forum. Edit 1 : I don't use VBAs, just basic Well, that's because you can't. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. Asked 9 years, 4 months ago. Active 2 years, 11 months ago.

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