Questions tagged [history]

The history of Unix systems and their main components. Please DO NOT USE this tag for shell-related questions; use "command-history" instead.

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Search in whole .bash_history list with full-featured regex engine

When I have to search backwards in the .bash_history list I want to see the timestamps as were created by HISTTIMEFORMAT. And the results have to end up in a pager, where regex can be used for ...
2 votes
1 answer
28 views

What is the history of /etc/mtab and what updated it?

I updated an old linux boot disk with new utilities and shared libraries. It still had an empty /etc/mtab to start with, on the old disk the /etc/mtab was updated, on the new one /etc/mtab stayed ...
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1 answer
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Has the linux kernel introduced incompatible changes to its "public API"?

I am trying to learn about Semantic Versioning, which states that the major version number should be bumped when an incompatible "public API" change occurs. My thought experiment is to try ...
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Which software emits dates in this format between dollar signs when exporting?

Sometimes I see dates enclosed in between two $ (dollar) signs, eg. $Date: 2018/11/11 10:05:10 $ or $Date: Tuesday 06 April 2004 - 14:10:05$. I've seen this mostly on personal homepages, most probably ...
23 votes
1 answer
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Why does `dd` use `=` in its parameters?

Why does dd use parameters with a = (if=/dev/zero) and not the more common approach of something like -i /dev/zero? I'm just curious if someone knows the historical reason or what the pros and cons ...
1 vote
2 answers
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Why is `-W` reserved for vendor extensions?

Why does the POSIX standard reserve the -W option for vendor extensions of the system utilities? I do not understand why the letter ‘W’ is used. ‘V’ (for vendor) could make more sense. Maybe this ...
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2 answers
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Did Unix have a package manager?

I've looked online but couldn't get a straight answer. Plus, there are no mentions of package managers on the Unix books that I've read. One would imagine that someone/something needed to manage the ...
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0 answers
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Why was semaphore part of Realtime rather than Pthread?

In my opinion, semaphore is a general-purpose synchronization primitive with a wide range of application. So why did the IEEE people initialy standardize it as part of Realtime extension rather than ...
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Alternative permissioning systems considered in the past?

I remember reading about a permissioning system other than the one we're used to in unix. If I recall correctly it was designed by someone on a team involved in the development of unix and never ...
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History : For what technical reason(s) GNOME was forced to remove its icons from the desktop by default?

I'm asking a question about GNOME History. I've red on few websites that GNOME developers where forced to remove the ability to put icons on desktop by default, for some technical reasons that I can't ...
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20 votes
4 answers
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What is `/dev/sda0`? Is it a standard thing?

While trying to understand this other question, I encountered /dev/sda0 being mentioned. I have some experience in Linux and I'm used to this scheme where sda, sdb, … are devices and sda1, sda2, … , ...
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1 answer
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HISTTIMEFORMAT messed up adb

I set up earlier this month HISTTIMEFORMAT cause I needed to see the time on some of the commands I previously used. However, I most likely messed something up with those commands, because every time ...
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Is there a way to timestamp the history in bash? [duplicate]

By default, history returns a list of commands and index numbers that can be used to rerun them. Is there a way to also add the timestamp to that list?
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Why does the option --add_extra_groups in adduser contain underscore rather than hyphen word delimiters?

Premise Most of the long-form options in the various *nix tools use hyphens as word separators. Examples from man tr: --squeeze-repeats --truncate-set1 from man sudo: --preserve-env --set-home --...
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Why is /bin merged into /usr/bin rather than the other way around? [duplicate]

I'm reading this document about the move towards merging /bin into /usr/bin: The historical justification for a /bin, /sbin and /lib separate from /usr no longer applies today. (More on the ...
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1 vote
1 answer
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Why is the prompt shown at the top of the terminal, rather than at the bottom?

Why am I asking this? As you can guess, it's mostly for curiosity. But why did the curiosity spring up in my mind? Well, there's been a moment when I noticed that I was not happy that after I'd run ...
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23 votes
3 answers
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Has Linux always separated User and Kernel space?

I was thinking back to my introduction to programming recently and remembered writing a C++ program that deliberately read and wrote to memory addresses at random. I did this to see what would happen....
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Why is unistd.h named the way it is?

Similar in spirit to this question about the etymology of linux commands, I'm curious about the origin of the name of unistd.h. From the Open Group's description of unistd.h (emphasis mine): unistd.h ...
0 votes
1 answer
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When was NSS (Name Service Switch) introduced in Solaris?

I was not able to find a date or a Solaris release number... Also, beside Ultrix's svc.conf system (mentionned in NSS's Wikipedia article), did other comparable systems exist in other Unices, before ...
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1 vote
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History expansion with a string containing whitespace

I've been using unix for awhile and haven't like to use !, which, for as long as I've used unix, I've interpreted as find the last command that begins with the string following !, but it seems to not ...
0 votes
1 answer
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why no examples of video output in early computers (before desktop era) [closed]

Moved to https://retrocomputing.stackexchange.com/questions/23930/ (Retrocomputing community). Why was the serial terminal the dominant modality for interactive computer input and output up until the ...
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1 vote
1 answer
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Origin of date command default US format

date seems to have a very odd default format in the US locale: Thu Jul 9 17:00:00 EDT 2020 using a space-padded day-of-month and putting the (24-hour!) time in the middle, between the month+day and ...
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1 vote
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Were there any programs besides editors that relied on on the O_NDELAY file status flag (predecessor to O_NONBLOCK)

Recently, I've been researching on the O_NONBLOCK feature specified in the standard. From what I've seen so far, the predecessor of this flag - O_NDELAY had existed all the way back to UNIX System III....
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1 answer
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Deleting persistent shell history

Someone suggested this command to delete persistent shell history history -c; >$HISTFILE I just don't want to excute it before I know what it does exaclty, can you help?
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Single Unix Specification version 4 (Issue 7) moved bunch of Real-Time APIs to Base, What Next?

While reading the standard, I noticed that bunch of APIs were, Introduced in Issue 5 for alignment with POSIX realtime APIs, Marked for option group membership in Issue 6, and Moved to Base in ...
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15 votes
2 answers
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What is the bsdutils package on Debian? What is a "BSD-style Unix system"?

I stumbled upon the bsdutils package in Debian. The description says: This package contains the bare minimum of BSD utilities needed for a Debian system: logger, renice, script, scriptlive, ...
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1 answer
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Story about a complex solution vs letting it fail [closed]

I'm looking for a reference. It's a story about a team that solved a problem in a pretty complex way and the other simply let it fail, than the client would crash (or something like that) and it ...
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1 answer
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how to place a text in the command line

I have a script that reads a line from a file into variable foo. The line is in fact a long command that I often use as a template. I am trying to edit and re-use this long command. How can I place $...
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-1 votes
1 answer
355 views

Why does apt say "selecting previously unselected package"?

One of the most recognizable phrases of Debian-based GNU/Linux distributions is: Selecting previously unselected package pkg. It appears in the output of apt install pkg. Why? What is the benefit of ...
0 votes
2 answers
91 views

bash, pass an argument to the 'history' command

I do the following to make history more sensible (i.e. seeing when a command is run can be fairly critical when troubleshooting) shopt -s histappend; # Append commands to the bash history (~/....
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1 answer
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Any UNIX system that allow to move a file to a directory, rename file in the directory with +rw -x permission?

I'm trying to better understand how UNIX/LINUX file system works. file system-on-linux Compared to an inode, a directory structure contains a limited amount of information about a file. It only holds ...
-6 votes
3 answers
94 views

Why is the command called which and not where? [closed]

Why is the command called which and not where? Logically, you would want to search for the location of the executables, hence "where" are they, but not which.
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3 votes
0 answers
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Historical reason for function keys having non-consecutive key sequences in xterm

I'm using gnome-terminal as my terminal emulator, which sets TERM=xterm-256color. The key sequences sent when pressing the function keys F1, F2, … are as printed by $ infocmp -L1 | grep _f | sort -V ...
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0 votes
1 answer
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Alpine Linux - How to prevent .ash_history from being saved?

How can one prevent .ash_history from being saved at all in Alpine Linux?
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What does (or did) the name "feh" represent?

To me, the name of the feh image viewer is not memorable enough for me to recall it when I need it. I feel that if I had some context, I'd be able to remember it better. What, if anything, does the ...
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8 votes
1 answer
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Who decided the bc math library will define sine cosine and arctangent?

If you load the bc math library you get the trig functions s() and c() and a() which are sine, cosine, and arctangent respectively. Why these three functions? I know why it's those three from the ...
5 votes
1 answer
203 views

Difference between command `command` vs command `builtin` in Shell Scripting

I understand the command command is specified in the latest POSIX standard and builtin is not. I also realize that both commands are regular builtins (i.e. they can be overwritten by user-defined ...
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13 votes
1 answer
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Why do ^M and \r behave inconsistently?

Perhaps there are already answers out there that indirectly answer my question, but I've read many of them and haven't yet found a satisfactory answer to this discrepancy. The original meaning of ...
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2 votes
1 answer
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Why is not 'test -z =' an error after all?

I have a book that stated: "....For example, if the shell variable symbol contains an equal sign, look at what happens if you try to test it for zero length: $ echo $symbol = $ test -z "$...
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0 votes
1 answer
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Bash character ! of special history command

How do we change bash character ! for special history command to other direct single key character such as = ?
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5 votes
5 answers
668 views

why are the definition of true and false in stdbool.h the exact opposite from the UNIX programs true and false?

stdbool.h is usually defined as: #define false 0 #define true 1 (Sources: OpenBSD, musl, etc.) whereas the unix program false - which just has a unsuccessful status code, is defined as: int main(...
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5 votes
1 answer
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What format does syslog() use when writing to /dev/log?

I initially thought to post this to StackOverflow because my interest was primarily from a programming focus, but after reading about the history tag (and the question it linked to), I posted it to ...
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11 votes
1 answer
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What was the first file system in Linux distribution/s?

What was the first file system in Linux distribution/s? The "parallel" to FAT (?) in Windows at the early nineties? I want to know the name to read information about this; perhaps it was the ...
3 votes
0 answers
79 views

Why has ls never had a parsable option implemented? [duplicate]

So we all know you shouldn't parse ls for many reasons, mostly due to filenames allowing almost every character. However why has nobody been able to overcome this in an implementation of ls? Many ...
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2 answers
678 views

How to remove up arrow to search the history?

I am not really good with Linux but I got one premade server which has Linux on it to supervise. The OS is CentOS 7. I noticed that the up arrow allows the search of past commands (not only for the ...
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4 votes
3 answers
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Were there Unix equivalents to BBSes?

During the 1980s and 1990s Bulletin Board Systems (BBS) were widely used on all kinds of computers. The BBS Documentary documents the rise and fall of the BBS subculture. Watching this documentary ...
1 vote
1 answer
273 views

Since when do Unix systems support birth/creation time (btime/crtime) for files and directories?

Does anyone know when Unix supports birth/creation time stamps for files and directories? If possible also when first file manager (GUI) displays it by default for users. For comparison with Windows, ...
1 vote
2 answers
889 views

What is the historical reason for limits on file descriptors (ulimit -n)

When I first borrowed an account on a UNIX system in 1990, the file limit was an astonishing 1024, so I never really saw that as a problem. Today 30 years later the (soft) limit is a measly 1024. I ...
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4 votes
1 answer
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Why does ed support backreferences but not alternations in regular expressions?

I was looking into the history and development of regular expressions. I found the following timeline: 1956 - Kleene introduces regular expressions in his paper on nerve nets. 1964 - Brzozowsi ...
6 votes
0 answers
307 views

Why does ZFS rollback destroy intermediate snapshots?

Having used btrfs before, I was surprised to find out that rolling back a snapshot in ZFS not only changes the “working set” of files, but also requires that any snapshots which are newer than the ...
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