This command is light wight and straight forward. You just need to call this command with file name as an argument. You may have already know about command sed Stream Editor. Now, lets come to see how this command work. Which is useful for to shuffle lines. On every execution of this command you will get shuffled lines. The awk is the programming language which is specially designed for text processing.

We will use it to shuffle lines. Python is popular scripting language widely used today from big projects to small scripts. We will see, how you can shuffle lines using python. In this example, we are passing file name as command line argument. Reading it and shuffling the lines of file and printing them on terminal.

If you are looking for a quick shuffle command shuf is best choice or you can have a fun of using other ways to shuffle lines in the file. Your email address will not be published. Notify me of follow-up comments by email. Notify me of new posts by email.

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This is free software: you are free to change and redistribute it. If the info and shuf programs are properly installed at your site, the command info coreutils 'shuf invocation' should give you access to the complete manual.

GNU coreutils 8. Check Out this Related Man Page. Problem with sort-of array in SH. Hello to everyone! I'm really new in shell scripting and I'm experiencing a very odd problem. This is my first post in this forum, hope you can help! I know that declaring arrays in Bourne Shell is impossible. But this is where I start having problems - system administrator did not install Shell Programming and Scripting.

If file exists count lines. Adding new line character. Using and passing arguments to shuf within awk.

Hello all, I would like to output a random number within a range for every line using awk and shuf. Reshuffle values in a column. Hi, I would like to know how can I reshuffle values in a column from a text file. I know that shuf command does the trick of reshuffling values but how to substitute lets say the original values of column 9 of a text file by the reshuffling values? Thanks in advance 5 Replies. Failure using regex with awk in 'while read file' loop.

I have a file1. Using an labels. How to select lines randomly without replacement in UNIX? Dear Folks I have one column of lines and want to select randomly of them in five different times without replacement. I am aware that command 'shuf' and 'sort -R' could select randomly those lines but I am not sure how could I avoid the replacement of selection line. Does anyone have Cherry picking with sed? I want to reshuffle a deck but without the cards in RedHat Commands.

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shuf command in linux

FreeBSD Commands. Full Man Repository.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. It only takes a minute to sign up. I know this is sort of a duplicate of another question Why this sort command gives me an empty file? Returns a blank file, because the shell truncates the file before shuffling it, leaving only a blank file to shuffle. Why does the pipeline method work when the simple redirection doesn't?

If the file is truncated before the commands are run, shouldn't the second method also leave an empty file? So as there was no output yet, example. Your other command may suffer from the same issue. To avoid such issues entirely, you could use shuf example.

The package moreutils has a command sponge :. I removed the parallel installed by moreutils. Redirections are performed by the shell before the commands are executed and pipeline components are executed concurrently. From the GNU bash manual see also, for the details, section 3. Basically, the shell does the following:. Consider the situation where your file does not exist.

Yet your second example will create the file most of the times. If the file had not been so created and it didn't exist, and redirection hadn't occurred, cat would complain there is no such file Most of the time it won't. To reproduce the shuffle you got with that second command, I needed a great many tries. So indeed the second expression should leave an empty file most of the times. This opens the file, unlinks it, and then truncates the file. Thereby you avoid the truncated file before opening it, which is what you will normally see when redirecting output to the same file as you are reading from.

Sign up to join this community. The best answers are voted up and rise to the top. Home Questions Tags Users Unanswered. Asked 6 years, 2 months ago. Active 2 years, 8 months ago. Viewed 11k times. The command shuf example. However, cat example. Active Oldest Votes.

Or you could go with shuf example. StephaneChazelas, opening a file for writing with truncation is usually how you start writing to a file. It's quite hard to do without opening it.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service.

Ask Different is a question and answer site for power users of Apple hardware and software. It only takes a minute to sign up. Ubuntu Linux has a great tool called shuf, which works like head except that it gives you ten random lines. I couldn't find it on Homebrew. What is the simplest way of installing it on OS X?

shuf command in linux

Read the caveats when you install coreutils. Yet another solution is to learn about the tools supplied by the vendor.

Generating Random Numbers in Linux Shell Scripting

Certainly you could chain jotpastesortcuthead and get the same results. Another option is to install randomize-lines homebrew package, which has an rl command which has similar functionality to shuf. Sign up to join this community. The best answers are voted up and rise to the top. Home Questions Tags Users Unanswered. Install shuf on OS X? Ask Question. Asked 5 years, 8 months ago. Active 2 years, 1 month ago. Viewed 40k times. Active Oldest Votes. You can install coreutils with brew install coreutils.

Jay Thompson Jay Thompson 3, 16 16 silver badges 13 13 bronze badges. The caveat just seems to be that you shouldn't use the tools' proper names, but prefix them with g like "gshuf"right?

Yep, or optionally configure your PATH so you get what you expect. Mac OS X Catalina I had never heard about jot before. Thanks for expanding my knowledge. I used this one with macports, thanks. Great answer if you have sudo rights. I don't. Randomize the lines of a file or stdin. The Unfun Cat 1, 4 4 gold badges 13 13 silver badges 20 20 bronze badges. The Overflow Blog. Featured on Meta.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service.

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I want to shuffle the lines of a text file randomly and create a new file. The file may have several thousands of lines. You can use shuf. As jleedev pointed out: sort -R might also be an option. On some systems at least; well, you get the picture. It has been pointed out that sort -R doesn't really shuffle but instead sort items according to their hash value.

While it's true that the output order is determined by hash valuesthe randomness comes from choosing a random hash function - see manual. Note: These numbers were obtained on a late iMac with 3. While timings will vary with OS used, machine specs, awk implementation used e. Times are listed in ascending order fastest first :. Windows versions of the Python solution the Python code is identical, except for variations in quoting and the removal of the signal-related statements, which aren't supported on Windows :.

Note that PowerShell can natively shuffle via its Get-Random cmdlet though performance may be a problem ; e. I've also got a NULL-delimited version, called "unsort0" PS: Voted up 'shuf' too, I had no idea that was there in coreutils these days Here is a first try that's easy on the coder but hard on the CPU which prepends a random number to each line, sorts them and then strips the random number from each line.

In effect, the lines are sorted randomly:. But see this post for the drawbacks of python's random. It won't work well with many more than elements. It can be sorted via lexicographical order a. One liner for Python based on scai's answerbut a takes stdin, b makes the result repeatable with seed, c picks out only of all lines. A simple and intuitive way would be to use shuf.

If like me you came here to look for an alternate to shuf for macOS then use randomize-lines.On Unix systems, random numbers are generated in a number of ways and random data can serve many purposes.

Of course, this process is actually providing a "pseudo-random" number. As anyone who thinks about random numbers very often might tell you, numbers generated by a program have a limitation. If you need random numbers fairly frequently, maybe another seed would work better.

Here we're using the number of seconds since the Unix epoch. You can also use the shuf command to generate pseudo-random numbers. In the command below, we're generating 10 numbers between 0 and 32, The shuf command should start each sequence with a different number no need for seeding. For more serious requirements for random data, such as its use in encryption, some more truly random data comes into play. From the command line, these files look like this:.

Using the stat command, you can get a more descriptive listing than ls provides for either of these files. Notice the zero length and the date stamps. This file was generated when the system last booted. To get a feel for how much pseudo-random data is available in your entropy pool, you can run this command:.

The number shown appears to represent the number of bits of entropy that have been collected. Even 2, might not seem like much in a world in which we routinely speak in terms of terrabytes, but numbers above are said to be a good sign.

In addition, the number will change frequently. Check three times in a row, and you might see something like this. Entropy is reminiscent of a coin toss and is a measure of the uncertainty of an outcome, while randomness is related to a probabilistic distribution. For computer folk, the terms are often used as if they mean exactly the same thing. You can create a file of pseudo-random data if you need one.

Astuce Linux - 18. Tirer au sort et découvrir une commande (ls + shuf + man + sed)

Two of the options used with these of commands are particularly interesting. The -N controls the size of the output as the number in bytes.

How to shuffle lines in the file in linux

So, -N4 means the resultant number should be four bytes long. The largest numbers you will see will have ten digits. Also keep in mind that the entropy pool gets used up and regenerates.

More on this soon! Sandra Henry-Stocker has been administering Unix systems for more than 30 years. She describes herself as "USL" Unix as a second language but remembers enough English to write books and buy groceries. She lives in the mountains in Virginia where, when not working with or writing about Unix, she's chasing the bears away from her bird feeders.

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shuf command in linux

Sign Out Sign In Register. Latest Insider. Check out the latest Insider stories here. More from the IDG Network. Emerging Linux filesystems - Part 2. How to compress files on Linux 5 ways.You may have guessed that it is used to pseudo randomize a given input in the same way you would shuffle a deck of cards. You guessed right! Here we will cover the shuf command along with alternatives just in case you find yourself stuck without a shuf. Once you know what shuf is, the next step is knowing how to use it.

shuf command in linux

Like most command-line utilities, shuf comes with an —help long option. Each way has its advantages. Knowledge of all the ways beforehand may reduce the need to use other external commands in conjunction with the shuf command. File shuf is the most common way shuf is used in command line. When the -e or -i option are not included in the options, shuf will operate as file shuf. That is, the input to be shuffled will be a file whether standard input or any given file.

The last word in the parameter list may be a filename. In case this parameter is omitted file is taken to be standard input from the shell or piped. A — may be included following the convention that standard input is inferred. There is more than one way to specify the file using file shuf. Here are example commands for each way. In this way we omit file from the arguments of the shuf command.

Following the convention, you may opt to include a — in place of file to indicate the file to be taken as standard input. In this way, we specify a filename as file in the arguments of the shuf command. Here follow a few file shuf examples using files.

In the last way to shuf, we operated on a file or input piped into the shuf command.