Leading zeros printf bash

This is as much a reminder for myself as anything. I needed to create 31 folders named 00 through 31 for each day of the month in a web-directory used to store audio files from CAPE-1 transmissions. So, without much thought, I quickly typed the following into a shell on my web server:. OK, well that did create 31 directories, but the first 9 were named 1, 2, 3, etc. After a quick search on zero-padding in bash it seemed no one had posted anything about it except to say it was tricky. I could not think of any reason it would not work to deliver the argument to a mkdir statement, so I tried:.

And it works! Breaking the command down gives a standard bash for loop with the mkdir command as the internal command inside the loop. It seems like there should be a better way of doing this, but quickest way I found to add zero padding to a number in bash is to use the provided printf which uses the same formatting as the C language printf statement.

More usage and examples are available at the ss Man, this is great! Thanks a lot, this really made my day! I need to number thousands of files output from a scientific simulation and then concatenate them later in the right order, so I really need zero-padded numbers in the filename.

Glad you found it helpful. It does seem that there should be a cleaner way, but this was the best I found. Your article was really helpful! Thanks for the tips. For your particular case you can use seq no problem. So I used seq without -w as index and used your printf method to generate zero paddings when I need them in the filename.

Hopefully this saves one or two people a trip to the man pages. What I often do as a workaround is add or as it were so my ensemble runs and respective folders, files, … are numbered from to instead of 1 to That works also easily in Fortran and other funky languages. Calling printf will create a new process every time; this may be a little slow for some applications.

A better performing example:. On my machine at least running Debian 4. Benoit Terradillos Running your code under bash 3. Please make sure script Y is properly calibrated. Press any key to take shot! Bash interprets a leading zero on an integer constant as an octal number, which messes things up if you want to do decimal operations on that constant.

In fact, for a long time I used the korn shell ksh or pdksh for my scripts they use ImageMagick to add hh:mm:ss timestamps to images because the korn shell does not interpret constants with a leading zero as an octal, it just treats them like leading decimal zeroes. But now that I have found the printf statement, I can seq without -w, do my math and still create zero-padded strings when I need them. May 8, at am. Jonathan says:. Nikhil says:.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service.

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Bash: Removing leading zeroes from a variable

Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. If you want to use printfnothing prevents you from putting its result in a variable for further use:. Apparently this doesn't work on the newest versions of iOS, so you can either install macports and use its version of seqor you can set the format explicitly:. But given the ugliness of format specifications for such a simple problem, I prefer the solution Henk and Adrian gave, which just uses Bash.

Apple can't screw this up since there's no generic "unix" version of Bash:. I'm not interested in outputting it to the screen that's what printf is mainly used for, right? From bash 4. See below for the original announcement.

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This is a terse description of the new features added to bash Brace expansion now allows zero-padding of expanded numeric values and will add the proper number of zeroes to make sure all values contain the same number of digits. See help printf for this internal bash command. Learn more. How to add leading zeros for for-loop in shell? Asked 6 years, 7 months ago.

Active 2 years ago. Viewed k times. I have a basic number for loop which increments the variable num by 1 over each iteration Bruce Blacklaws Bruce Blacklaws 1, 2 2 gold badges 12 12 silver badges 14 14 bronze badges.

Use printf with an appropriate format.

leading zeros printf bash

Aug 27 '13 at There's mawk, gawk, awk, nawk, etc. I try not to recommend it because it seems like I can only test it on the computer I'm writing it on. Active Oldest Votes. Best answer, and it avoids using clumsy external commands like 'seq', not necessary in proper Bash.

Helped me.

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I'm on a server with bash 3. On my desktop with 4. Matt What exactly does not work? As long as you have a recent enough version of bash this works fine.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. The dark mode beta is finally here. Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information.

For example, I want to count from to Meaning the zero buffer would start off with 2, 1, then eventually 0 when it reaches or more. But that's static and not dynamic and would not work in my example. If by static versus dynamic you mean that you'd like to be able to use a variable for the width, you can do this:. Otherwise, the only reason your example doesn't work is that you use "2" perhaps as if it were the maximum padding to apply when it should be "3" as in my example since that value is the resulting total width not the pad-only width.

If your system has it, try seq with the -w --equal-width option:.

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In Bash version 4 use bash -version you can use brace expansion. Putting a 0 before either limit forces the numbers to be padded by zeros. All you need to do is change the max variable and it will handle the rest. This would print out, I didn't find any of the current answers meeting my need.

Learn more. In bash, how could I add integers with leading zeroes and maintain a specified buffer Ask Question. Asked 9 years, 9 months ago. Active 3 years, 1 month ago. Viewed 40k times.

leading zeros printf bash

Welcome to StackOverflow. Be sure to select the answer via the checkmark that you feel best resolves your question so others can benefit from the knowledge put forth. Active Oldest Votes. Paused until further notice. Yes, you're probably right about using zsh in a bash script.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 am currently looking for an alternative to the following code that works a little less 'wonky'. I am wondering if there is another way I can be a little more forgiving on the input or with the read command? Note that in bash, you can assign the results of a printf to a variable directly using -v e.

See also How do I stop Bash from interpreting octal code instead of integer? Sign up to join this community. The best answers are voted up and rise to the top. Home Questions Tags Users Unanswered. Add leading zeroes to a user's input but is being transformed with printf Ask Question. Asked 10 months ago. Active 10 months ago. Viewed times.

Michael Michael 33 3 3 bronze badges. Active Oldest Votes. The leading zeros on the input value are causing the shell to interpret it as an octal number. You can force decimal conversion using 10 e. I couldn't get that to work for me bash 4. Ah, it's not portable. Seems to based on what printf 3 does. In Bash, you can get rid of any prefixing zeros. Sign up or log in Sign up using Google. Sign up using Facebook.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service.

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Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. I'm trying to find a good way to print leading 0's, such as for a zipcode. While the number would be stored aswhat is a good way to do it? The 0 indicates what you are padding with and the 5 shows the length of the integer number. Despite the fact that it may look like a number, it isn't. It's a code, where each part has meaning. Zipcode is a highly localised field, many countries have characters in their postcodes, e.

For d, i, o, u, x, X, a, A, e, E, f, F, g, and G conversions, the converted value is padded on the left with zeros rather than blanks. If the 0 and - flags both appear, the 0 flag is ignored. If a precision is given with a numeric conversion d, i, o, u, x, and Xthe 0 flag is ignored. For other conversions, the behavior is undefined.

Even though the question is for C, this page may be of aid. You will save yourself a heap of trouble long term if you store a zip code as a character string, which it is, rather than a number, which it is not.

More flexible. Here's an example printing rows of right-justified numbers with fixed widths, and space-padding. Learn more. Printing leading 0's in C? Ask Question. Asked 11 years, 6 months ago. Active 6 months ago. Viewed k times. Active Oldest Votes. AJFarmar 11k 2 2 gold badges 31 31 silver badges 57 57 bronze badges. EvilTeach EvilTeach Please do not store zipcodes as numbers.

Some countries have letters in their zipcode. For your case, this would suffice.

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How can one have leading zeroes in an integer of unknown length? You need to know the maximum length of the final padded string. A number is a thing you do arithmetic on. A zip code is not that. Martin Tournoij James Curran James Curran Your observation is absolutely correct.Today's Posts.

leading zeros printf bash

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Show Posts. Shell Programming and Scripting. Add leading zero's to the number in unix. Registered User. Join Date: Nov Hi, Can anyone help me how to add leading zero's 0's infront of numbers in unix script. For more details. Last edited by easterraj; at AM.

Code :. Last edited by Scrutinizer; at AM.

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Reason: The OP has changed his requirements. Join Date: Feb Originally Posted by easterraj. Add leading zero's to the numbers in unix. Hi, Help me I have to add leading zeros of two numbers. How can i add leading zeros infront of the numbers. Try: Code :. Join Date: Oct If you're using ksh No need for awk: Code :. Ho to remove leading zeros from a csv file which is sent from a UNIX script. Hi All, I am using a informatica job to create a csv file and a unix script the mail the generated file. Everything is working fine but I am not seeing leading zeros in the csv file sent in the mail.

These zeros were present when the. Is there any How to add line number using UNIX command? Hi, I am working on Shell script and I have a. Please see below example file Input File: C A I AJon, United States express iceland, July 2015 This was a wonderful vacation. Ricardo, United States express iceland, July 2015 Booking with Nordic Visitor was the best choice made.

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