The opposite day I used to be testing alias and unalias instructions on my Ubuntu 18.04 desktop. I wished to refer all out there arguments, flags and choices of the alias command, so I opened the person web page. However, I bought the next message after I tried to open the person pages of alias or unalias instructions.
$ man alias
No guide entry for alias
$ man unalias
No guide entry for unalias
It seems that man pages are lacking for another applications, equivalent to export and eval.
There isn’t a different method besides googling to find out about these applications.
On RPM-based techniques(E.g. CentOS), in the event you run “man alias” command, it should open man pages for BASH BUILTINS. You might must undergo the entire man web page to search out particulars of the respective command.
After a little bit of Google search, I discovered that there isn’t a devoted guide pages for shell builtins, like alias, export, eval in Linux Programmer’s guide. In case you’re unsure whether or not the given command is an alias, shell built-in, file, perform, or key phrase, use kind command to search out out.
$ kind alias
alias is a shell builtin
The documentation for these builtins can be found within the associated shell man web page. As you possibly can see within the above output, alias is a shell builtin, so you possibly can view the documentation within the related shell man web page. In my case, it’s BASH.
Allow us to open the person pages of BASH:
$ man bash
Seek for alias or unalias entries within the Bash man web page.
Right here is the knowledge of alias and unalias:
Tip: Having hassle at discovering one thing within the man pages? Refer the next information.
View details about shell builtins utilizing “assist” command
Alternatively, you will get the knowledge of shell builtins utilizing assist command like under.
$ assist alias
alias: alias [-p] [name[=value] … ]
Outline or show aliases.
With out arguments, `alias’ prints the record of aliases within the reusable
kind `alias NAME=VALUE’ on customary output.
In any other case, an alias is outlined for every NAME whose VALUE is given.
A trailing house in VALUE causes the following phrase to be checked for
alias substitution when the alias is expanded.
-p print all outlined aliases in a reusable format
alias returns true except a NAME is equipped for which no alias has been
In case you favor man web page format, merely use -m flag with assist command under.
$ assist -m alias
All bash builtins have assist pages. Even assist command itself has a assist web page.
$ assist assist
assist: assist [-dms] [pattern …]
Show details about builtin instructions.
Shows temporary summaries of builtin instructions. If PATTERN is
specified, provides detailed assistance on all instructions matching PATTERN,
in any other case the record of assist subjects is printed.
-d output quick description for every subject
-m show utilization in pseudo-manpage format
-s output solely a brief utilization synopsis for every subject matching
PATTERN Sample specifiying a assist subject
Returns success except PATTERN shouldn’t be discovered or an invalid choice is given.
That is how you’ll find the knowledge of shell builtins.
Now, allow us to get again to the subject. Is there any option to set up lacking man pages of instructions? That’s what we’re going to do now.
Set up Lacking Man Pages Of Instructions On Ubuntu
As acknowledged earlier, Builtins are a part of the shell. Every shell has its personal set of builtins. They aren’t unbiased instructions they usually don’t have separate man pages. Fortunately, the person pages of shell builtins can be found in POSIX Programmer’s Guide. You must set up it to entry these man pages.
On Debian, Ubuntu and different DEB-based techniques, merely run the next command to put in POSIX Programmer’s Guide:
$ sudo apt set up manpages-posix
Now, you possibly can entry the person pages of a shell builtin (E.g. alias) utilizing command:
$ man alias
Hope this helps.
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