GNU Core Utilities are the GNU project's implementation of the core command-line tools of a POSIX system, including tools like ls, cp, mv, rm, etc.

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39
votes
3answers
5k views

How does `yes` write to file so quickly?

Let me give an example: $ timeout 1 yes "GNU" > file1 $ wc -l file1 11504640 file1 $ for ((sec0=`date +%S`;sec<=$(($sec0+5));sec=`date +%S`)); do echo "GNU" >> file2; done $ wc -l ...
3
votes
1answer
37 views

How to find out if a file on btrfs is copy-on-write?

I know that cp has a --reflink option to control full copies vs. copy-on-write "copies". On btrfs, can I use ls (or some other command) to find out whether a file shares (in a copy-on-write senses) ...
0
votes
0answers
30 views

what's the use of yes (coreutils)? [duplicate]

I notice my shell has a util named "yes" It just output a infinite "y" string line by line What's the use of this "core util" of "yes" ? Usage: yes [STRING]... or: yes OPTION Repeatedly output a ...
3
votes
3answers
44 views

Symmetric Difference Pipe?

I have a command that produces a lists of strings followed by newlines, a, and a file containing a list of strings followed by newlines, b.txt. I need a command that calculates the symmetric ...
0
votes
1answer
55 views

Strange cut behavior

I'm using cut (GNU coreutils) 8.24. The command: echo "TEST=test" | cut -d"=" -f2- outputs Ttest. I don't think this is the intended behavior. Am I using it wrong or is there something wrong with my ...
0
votes
2answers
27 views

Unix equivalent of `du -sb` to get summarized size in bytes

On Linux using GNU du to calculate the size of directory recursively in bytes I can run: du -sb /etc What is equivalent syntax for BSD du based on the fact that -b parameter is not available?
0
votes
0answers
40 views

LFS error - Coreutils (step 6.29)

As succinctly as I can put, I've gotten all the way to 6.29 in the book (Coreutils) and I seem to be receiving the following error when running the "make" command. Full output is as follows: ...
4
votes
1answer
69 views

Why does a '.' work in chown?

Why does GNU chown user.group work? The docs say nothing of the syntax being supported. Is there a juicy story behind it?
4
votes
1answer
211 views

`set -e` and `grep` idiom for preventing premature exit from shell script when pattern not found

Help required - in the context of shell scripting on a GNU/LINUX bash: I always use set -e. Often, I would like to grep and do not always want the script to terminate execution if grep has an exit ...
9
votes
5answers
1k views

Is there a practical use for the GNU factor command?

Looking through the GNU Coreutils, I spotted the factor command, that I had never noticed before. Reading the man page: Print the prime factors of each specified integer NUMBER. If none are ...
11
votes
2answers
1k views

coreutils that are utf aware?

When I used cut today, I found out it doesn't treat a UTF-8 character as a character, but 3 characters because it's 3 bytes long. This seems to be generally true for many tools. Are there versions ...
2
votes
2answers
284 views

Has the GNU coreutils stat tool changed?

Has the GNU coreutils (8.6) version of stat changed? After a recent update, some scripts I wrote that call stat are not working as expected; in particular, I had been making use of stat -c %Y ...
0
votes
1answer
50 views

Error in 'date -d' command

Hmmm... Right now (Sat Oct 24 00:36:56 CDT 2015) on my Arch Linux system there appears to be a problem with the date command: $ date -d "+8 days" "+%A %d %B %Y" Sunday 01 November 2015 $ date -d "+9 ...
4
votes
1answer
87 views

mv overwrites read-only file without prompting

The GNU Coreutils manual for mv says: If a destination file exists but is normally unwritable, standard input is a terminal, and the -f or --force option is not given, mv prompts the user for ...
5
votes
1answer
71 views

When is next Monday?

On my home computer (Xubuntu 14.04), I have zev@home:~$ date +%F 2015-10-05 zev@home:~$ date +%F -d "next Monday" 2015-10-12 whereas at work (Red Hat 5.11), I have zev@work:~$ date +%F ...
2
votes
1answer
165 views

Installed coreutils on CentOS for sort --human-readable flag but it still doesn't work

I'm trying to do du -h | sort -h, but my CentOS 5.7 doesn't have -h flag for sort. So I installed coreutils Updated: coreutils.x86_64 0:5.97-34.el5_8.1 Complete! yet sort still doesn't have ...
6
votes
1answer
144 views

How can I delete a file named “--append”? [duplicate]

By mistake I have created a file named : --append. How do I delete it? Simply entering the usual command, rm -f --append, doesn't work.
25
votes
2answers
1k views

Why does ln -s accept a single argument

> cd /tmp > ln -s foo > ls -alhF /tmp lrwxrwxrwx 1 user user 3 Jul 29 14:00 foo -> foo Is this a bug in ln or is there a use case for symlinking a file to itself? This is with ...
8
votes
5answers
622 views

How intelligent are unix utilities?

Unix utilities like sort, find, grep, diff et al are very handy to perform quick tasks, sometimes without writing any code at all. I wanted to know what algorithms do they internally use and how do ...
5
votes
1answer
137 views

Is there a command line tool to manage unix signals?

Is there a command runner like env, nice, nohup, etc., that can run a program with modified signals? In my case, I need something to reset SIGINT to SIG_DFL. Why do I need this? Because ...
2
votes
1answer
267 views

sudo ls not showing hidden files on Linux

Today I discovered that sudo ls shows hidden files (that is, those that have names starting with .) on OS X. This surprised me so much that I asked a question about this behaviour, which I still find ...
43
votes
11answers
29k views

Correct locking in shell scripts?

Sometimes you have to make sure that only one instance of a shell script is running at the same time. For example a cron job which is executed via crond that does not provide locking on its own (e.g. ...
16
votes
4answers
3k views

Why is cp --reflink=auto not the default behaviour?

Why is cp --reflink=auto not the default behaviour? Could it cause any harm to enable it? Is it possible to enable it at compile time, so it is used all across the system, not just in interactive ...
6
votes
1answer
1k views

How does the “1 month ago” option in date command work?

I'm not sure if this gets the past date within the current day or if it only takes 30 or 31 days to it. e.g. If the current date is March 28th, 1 month ago must be February 28th, but what happen ...
4
votes
2answers
297 views

change file size format when using stat

The formatting character %s makes stat print the filesize in bytes # stat -c'%A %h %U %G %s %n' /bin/foo -rw-r--r-- 1 root root 45112 /bin/foo ls can be configured to print the byte size number ...
9
votes
4answers
44k views

Storing output of command in shell variable [duplicate]

I have an operation using cut that I would like to assign result to a variable var4=echo ztemp.xml |cut -f1 -d '.' I get the error: ztemp.xml is not a command The value of var4 never gets ...
0
votes
1answer
152 views

cp options --no-clobber vs. --update

I want to copy a single file if (and only if) the destination does not exist. The source file changes rarely, maybe once a month. The destination almost never exists. Are there any differences ...
9
votes
3answers
536 views

Which version of X introduced feature Y?

A big part of my daily job is developing software for use on machines with different versions of the same software, like bash, find, and grep. When encountering a feature which would be useful for ...
2
votes
1answer
450 views

what are practical uses of stdbuf or nohup?

I have to finish a writeup of a few coreutils commands for a course at the moment, and I can't think of a starting point for a small practical code example that demonstrates the potential uses of ...
13
votes
3answers
859 views

/usr/bin/ptx: Can you provide a use case or two?

I was going through the list of files included in coreutils and I was able to come up with an example of how I could personally use all of the commands provided except for ptx. Can you give one or two ...
0
votes
1answer
137 views

*ls* font differences between files and folders with “--color” option

I have recently switched to urxvt from xterm for better unicode support and it does much better as to the font fallback. However I find an interesting issue: names of files and folders are rendered ...
2
votes
1answer
153 views

How can I cross compile the dd linux tool for arm?

I need to cross-compile a full version of dd because my device only has a busybox one that doesn't support many options. Where do I get the source for it? I've been looking on the kernel repo online ...
2
votes
5answers
6k views

ls command - define number of columns

Is there a way to define the number of columns in ls output? I got this far: ls -C sorts in columns and ls -1 produces one column. --tabsize = option to produce two columns resulted in what looks ...
4
votes
1answer
1k views

Install only a few GNU coreutils?

Is there a way to build and install only a few of the GNU coreutils? The README in coreutils-8.19.tar.xz lists 100-odd, but the INSTALL doesn't say how to install only a few, and the Makefile is (to ...
8
votes
2answers
1k views

How is the order in which tar works on files determined?

$ touch dir/{{1..8},{a..p}} $ tar cJvf file.tar.xz dir/ dir/ dir/o dir/k dir/b dir/3 dir/1 dir/i dir/7 dir/4 dir/e dir/a dir/g dir/2 dir/d dir/5 dir/8 dir/c dir/n dir/f dir/h dir/6 dir/l dir/m dir/j ...
10
votes
3answers
10k views

Mac OS X: dircolors not found?

I just switched to a Macbook Air. I installed zsh using homebrew, but when I use some of the code that I (originally had) in my .zshrc, I get an error saying that .dircolors was not found. Below is ...
2
votes
1answer
61 views

Difference between / and // [duplicate]

On the bash prompt one, three or more slashes (/,///,////, ...) are treated as a single slash, whereas two slashes (//) are left as is: 12:07 $ cd / 12:07 $ pwd / 12:07 $ cd // 12:07 $ pwd // 12:07 $ ...
18
votes
3answers
2k views

Why is coreutils sort slower than Python?

I wrote the following script to test the speed of Python's sort functionality: from sys import stdin, stdout lines = list(stdin) lines.sort() stdout.writelines(lines) I then compared this to the ...
0
votes
0answers
23 views

Set default editor for 'info coreutils' [duplicate]

I'm using Ubuntu 14.04 and have this in my .bash_profile: export EDITOR=/usr/bin/vim export VISUAL=/usr/bin/vim man respects this setting but info always opens in something else, nano or it's own ...
3
votes
2answers
364 views

Is grep part of coreutils? (If not, why?)

I have read in a few websites that grep comes with coreutils (e.g. https://wiki.archlinux.org/index.php/Core_Utilities) However, after building them, I noticed that grep is missing. I wonder if I ...
0
votes
1answer
171 views

Why can't my `date` deal with timezones? [duplicate]

I'm having some weird issues with GNU coreutils date v8.4 (CentOS) that aren't occurring in v8.21 (Ubuntu/Mint). On v8.4, I get the following output (I'm in PST): $ date --version | head -n 1 date ...
2
votes
1answer
562 views

Problem with install command to copy a whole directory

So I have a repo with some of my config files and I'm trying to create a makefile to install them in the homedir. The problem I have is that when I run the following command straight in bash install ...
0
votes
2answers
530 views

Permissions for installing coreutils with pkgsrc on NetBSD

I'm trying to install coreutils on NetBSD 6.1.5 using the pkgsrc system. This is on the default install of 6.1.5. The only change made has been to install zsh and set it as my default shell for users ...
9
votes
2answers
9k views

GNU “install” -d flag — how's it work?

I'm trying to write a makefile rule to copy a directory, maintaining its structure, and since all the other rules in our makefiles use install, I wanted to be consistent. In the manpage, it says: ...
2
votes
1answer
88 views

Where is using @ before a date string for seconds since the epoch documented?

GNU date and touch commands (and presumably others) use @date to define a date string as seconds since the epoch. For example: $ TZ=UTC date -d@10 Thu Jan 1 00:00:10 UTC 1970 I was answering a ...
9
votes
3answers
11k views

How can I display octal notation of permissions with ls - and can octal represent all permissions? [duplicate]

After looking at the man page for ls on my system and searching Google, I see there IS a hack of way to use awk or perl to show octal permissions when using ls, but with bash is there anything more ...
2
votes
3answers
442 views

When was a file last opened?

How do I determine, when a file was last opened? I've looked at man ls (using GNU coreutils 8.22) and I don't see anything about this timestamp.
8
votes
2answers
977 views

sort by hex value

Using coreutils sort, how can I sort numerically by a hexadecimal value (field)? I was expecting something along the lines of sort -k3,3x file_to_sort however, such an x does not exist. Edit: ...
3
votes
2answers
497 views

See extended attributes with coreutils ls on Mac

I have coreutils installed via MacPorts on my Mac running OS X 10.8.4. I have ls set to use the coreutils version of ls [(GNU coreutils) 8.21] when available: if [ -e /opt/local/libexec/gnubin ]; ...
0
votes
2answers
83 views

Where can I view a changelog for the sort command

I need to find sort's version when the -V flag was introduced. But I am finding myself some hard time finding the changelog for this command. Where can I view it?