I see many times flags such as if [-n ${Parameter}] or echo -n <string>. Sometimes, I have seen flags like -r and others used. However, I don't know how to search for the meaning of these flags on web. Could someone send me some link where I can understand as to what they mean or some general note as to how should I search for them on google? Thanks!
You can of course check the doc on internet https://ss64.com/bash/if.html
Or if you have access to a linux or mac machine, just check out the installed doc !
Try man if for example.
Also, man could have multiple pages for the same query, for example man open will show the manual of openvt on my machine and is a command line executable. But writting man 2 open gives you the manual of the C open function.
So by default man gives you manual of bash/command line and then C function.
So man open could be written man 1 open
This is really useful if you don't have an internet access or if the version of the tools that you want to use is different from the "normal" one. I think about sed for example, that is different from linux and mac. So they has different manual.
Of course there is a man of man ... :)
man man
I forgot to talk about help, most (and decent) program has the -h or/and --help. Most of the time the manual page shows much more information.
Related
I am trying to install a man page for a bash script on Mac OS X 10.9.5. The procedure that I tried to follow is summarised here: man page tutorial. I also summarise the steps that I tried below:
cp custom_command.1 /usr/local/man/man1/custom_command.1
gzip /usr/local/man/man1/custom_command.1
When trying man custom_command I receive the output No manual entry for custom_command. I also tried other installation methods mentioned in man page tutorial.
It is interesting to note that the steps above worked for the emacs console, i.e. I do get the correct manual when I type man custom_command. However, the command is not recognised by the autocomplete and I receive the following warning before I am able to read the manual: WARNING: terminal is not fully functional.
Any advice on how to resolve the issues above (i.e. both with the system terminal and the emacs console) would be appreciated.
Remark 1
For a reference, the man script that I am trying to install was taken from the tutorial and is restated below for a reference:
.\" Manpage for nuseradd.
.\" Contact vivek#nixcraft.net.in to correct errors or typos.
.TH man 8 "06 May 2010" "1.0" "nuseradd man page"
.SH NAME
nuseradd \- create a new LDAP user
.SH SYNOPSIS
nuseradd [USERNAME]
.SH DESCRIPTION
nuseradd is high level shell program for adding users to LDAP server. On Debian, administrators should usually use nuseradd.debian(8) instead.
.SH OPTIONS
The nuseradd does not take any options. However, you can supply username.
.SH SEE ALSO
useradd(8), passwd(5), nuseradd.debian(8)
.SH BUGS
No known bugs.
.SH AUTHOR
Vivek Gite (vivek#nixcraft.net.in)
First of all you may want to check if the man page your are trying to install is properly formatted and can be opened by man command. To do this pass the path to the man file to man command. It must contain a slash in order to be recognized as a path, for example:
man /usr/local/man/man1/custom_command.1
Then you should make sure the path you are installing your man page to is on the search list of man command. In order to find the man page its path must be either:
specified with -M option to the man command
set in the environmental variable MANPATH
listed in its config file (/private/etc/man.conf on OS X) under MANPATH statement or under MANPATH_MAP statement (which applies only to locations in your PATH environmental variable)
located in the location relative to where binary is installed, i.e.: if binary is installed in path/bin the man page is searched for in path/man, path/cat and path/bin/man, path/bin/cat
listed in files added in /private/etc/manpaths.d/ directory
The name of the man page file must be same as command name with optional section number. It may be gzipped.
To see where man will search for your custom_command man page run
man -d custom_command
OS X user command man pages are typically created in:
/usr/local/share/man/man1
If you prefer to create man pages in a different directory edit:
/private/etc/man.conf
Then add the new path to MANPATH_MAP, for example:
MANPATH_MAP /usr/local/bin /usr/local/man
To have man search a non-default path with a default fallback (/usr/local/share/man):
MANPATH /usr/local/man
MANPATH /usr/local/share/man
MANPATH_MAP /usr/local/bin /usr/local/share/man
Manual pages in MacOS X
The man command in MacOS X uses a sophisticated method of finding manual page files, based on the invocation options and environment variables, the /private/etc/man.conf configuration file, and some built in conventions and heuristics.
In MacOS X you have a command:
/usr/bin/manpath
That lists all your current locations for searching for man pages.
It can be invoked by just typing
manpath
in a Terminal.
It does not however add this to your $MANPATH shell variable.
But you'll still have access to the manpages with the man command.
What get's included in manpath is defined in
/private/etc/man.conf
It's not advised to export an environment variable called MANPATH without adding the output of:
`manpath`
to the list.
So if you want to export $MANPATH to your shell environment, do it like:
export MANPATH="`manpath`:/path/to/man/pages/to/include"
That way you'll get a complete list of manpages defined by the OS and any paths you add yourself.
For more info, open up a terminal and check:
man manpath
and the man.conf file with:
more /private/etc/man.conf
Usually a better option for including man pages in peculiar places, is to create a symlink to the directory containing the man pages in /usr/local/share/man which is indexed by the "man ecosystem" by default.
I had installed packages via brew, but the man command was drawing a blank because I had installed brew to a different directory.
To get round this, still linking the packages (which linked content up a few directories), I could then add to MANPATH in my .bash_profile, like so...
MANPATH="/Users/me/Developer/share/man:$MANPATH"
While existing answers do provide some hints/options which can help solve the OP's problem, they do not actually answer the question in title.
Indeed, in order for the man program to open the man page, it should know where to look for it. This is an obvious statement, but it doesn't help much. The question is whether you should use some "standard" location (and if so, what are those "standard" lookup paths, and where are they defined), or should you place the man page along with your program, and somehow point the man program to your custom location?
The OP seems to have tried placing the man page to what he thought was a "standard" location (/usr/local/man), but the man was unaware of it.
It should have worked if, instead of /usr/local/man/man1/custom_command.1, a /usr/local/share/man/man1/custom_command.1 was used. How could you know this? The answer is in the /etc/man.conf:
#
# Every automatically generated MANPATH includes these fields
#
MANPATH /usr/share/man
MANPATH /usr/local/share/man
MANPATH /usr/X11/man
MANPATH /Library/Apple/usr/share/man
/etc/man.conf is used to configure the default manpath (the provided example is from the default man.conf in macOS Big Sur). That being said, I don't think relying on man.conf default configuration and simply copying the man page for your custom program/script to one of these directories is the right thing to do.
The reason is that the default manpath is configured according to the man.conf only if the $MANPATH environment variable is not set or is empty. If the $MANPATH environment variable is set/not empty, the paths in the /etc/man.conf are not used to look up the man pages.
By default, $MANPATH is not set. But if your program/script + man page will be distributed to other users, you can't be sure whether or not it's set there.
So, what would be a reliable solution? In my opinion, shipping the man pages along with the script, and using the path_helper (man path_helper for more info) to point man to the custom manpath is the best way to go for third-party programs.
From the program/script author the only thing that's needed is to place the file, containing the path to the program man pages, into the /etc/manpaths.d directory. path_helper should do the rest.
It seems that path_helper was designed specifically for such use case, and it's being used by third-party programs (I learned about it after installing Wireshark and while trying to make its man pages discoverable), but there is one caveat:
path_helper will not make the man aware about your custom manpath, if the $MANPATH environment variable was not previously set (and as we know, it's not set by default). From path_helper man page:
(The MANPATH environment variable will not be modified unless it is already set in the environment.)
And this is the reason why you would actually want to set the $MANPATH, to allow the path_helper to augment it with custom manpaths afterwards.
In my case I added export MANPATH (just to set it, without any value) to /etc/zshenv (I am using macOS Big Sur, zsh is the default shell), and path_helper successfully added all the custom manpaths from /etc/manpaths.d files.
Besides all the entries pointed out in baf's answer, there's also /etc/manpaths, which is quite convenient to use for including man pages installed via Homebrew.
For example, below is the content of my /etc/manpaths:
/usr/local/opt/coreutils/libexec/gnuman
/usr/local/opt/findutils/libexec/gnuman
/usr/local/opt/gawk/libexec/gnuman
/usr/local/opt/gnu-sed/share/man
/usr/local/opt/readline/share/man
/usr/local/share/man
/usr/share/man
Meanwhile make sure in /etc/profile, MANPATH is defined before path_helper is loaded:
export MANPATH= # hack: path_helper doesn't setup MANPATH without this
eval `/usr/libexec/path_helper -s`
BTW, in macOS, the default pager is /usr/bin/less is a bit old, and doesn't even support \b for word boundary in regex, so you might want to setup MANPAGER in ~/.bashrc (or somewhere you prefer):
export MANPAGER=/usr/local/bin/less
If the possible is following, could someone help me do it?
I want to customize the Windows 7 command prompt (cmd.exe) so that instead of it showing C:\Users\Blah> , it shows
[HH:MM] text#text ~ $
Essentially, I want to make it look like it's Arch Linux but it's not.
/halp
As foxidrive says in comment, the built in help documentation for PROMPT describes the available meta characters for the PROMPT command.
There is no direct way to get time as HH:MM. You will have to use backspaces to strip off the minutes and seconds. Also, hours less than 10 may have a leading space instead of a leading zero, depending on regional settings.
prompt [$T$H$H$H$H$H$H] text#text ~ $$
Try Clink which supports customizing the prompt with Lua scripts, as well as adding Bash-style line editing, completion, and history just like Arch Linux.
For example, I want to know what -r does in terminal. I can't easily find any documentation but I assume in terminal there must be way to have a command explained. I tried info [-r] and help -r, but these combinations haven't worked. I'm sure it is very simple. Thanks.
Each command-line tool supports different options.
There is no standardization, even if a lot of commands implement the same arguments for the same actions (as -r).
So you need to get help on a specific command.
You can do it with the man command, to get the complete manual of the command:
man [COMMAND]
Like:
man ls
A lot of commands also implements the --help or -h arguments, for a shorter help dialog.
I would like to compare all GNU Unix manuals and and Mac's Unix manuals by sdiff.
I do not know how you go through, for instance, all Mac's Unix manuals and then save them to a file.
The comparison can be done by the following code when the manuals are in two files
sdiff <(file1) <(file2)
Perhaps, there is some index of Unix command names such that we can do the following
sdiff <(man *[in the index]) <(man *[in the index])
How can you compare all GNU Unix manuals with all Unix manuals in Mac?
[edit]
Mac's manuals are at /usr/share/man/man[1-9]/*.
I have an encoding problem with them when I try to cat them.
Another problem is to find the location of Coreutils' manuals.
Your goal, to identify the differing parameters for the different BSD vs GNU/Linux versions of the various programs, is going to be somewhat tedious. It's useful to note that there are other variants of all commands as well. There are system V versions and BSD versions and GNU versions, and the Mac uses a mish-mash of all 3. In any event, as a starting point, the files themselves are filled with formatting macros that you have no interest in. Pipe the output of man through 'col -b' to get data you can diff. In terms of generating the list of commands, you could just ls -1 /bin /usr/bin' Then something like this would get you most of the way:
while read command ; do
man $command | col -b > output1
man ./path/to/GNU/$command | col -b > output2
diff output1 output2 | grep '^[ ]*-' > $command.diffs
done<<EOF
diff
grep
sort
...
...
EOF
GNU means (G)NU is (N)ot (U)nix. GNU is not based, in any way on UNIX, it could not be due to copyright and licensing issues.
Most GNU documentation was written in texinfo format (which Debian later converted to roff (man) format as users wanted man pages). The documentation is in no way based upon the BSD documentation, everything in GNU was written from scratch.
Trying to diff between the two is like diffing a dictionary against a thesaurus. You will find that they both contain many of the same words, but are entirely different books written by entirely different people.
The documentation in no way adequately explains the differences between GNU and BSD (and by extension MacOS).
All man pages exist within the /usr/share/man/*; I'm not sure what you are attempting to accomplish here. Mac runs on BSD, so most applications are going to be the same as the ones you would find on the BSD machine. If you still wanted to do it, you would need to grab the manual pages of the same applications in *nix as in Mac as well as the same version (since the man page can change). And yea, I would say that doing a diff /usr/share/man/man[0-9]/* and the expanded tar of all the man pages from the linux box.
In bash, environmental variables will tab-expand correctly when placed after an echo command, for example:
echo $HOME
But after cd or cat, bash places a \ before the $ sign, like so:
cd \$HOME
If I use a variable as the second argument to a command, it won't expand at all:
cp somefile $HOM
What mysterious option do I have in my .bashrc or .inputrc file that is causing me such distress?
What you're describing is a "feature" introduced in bash 4.2. So you don't have any mysterious option causing you distress, but just "intended" behaviour.
I find this very annoying since I preferred it the way it used to be and haven't found any configuration options yet to get the earlier behaviour back. Playing with complete options as suggested by other answers didn't get me anywhere.
Try complete -r cd to remove the special programmatic completion function that many Linux distributions install for the cd command. The function adds searching a list of of directories specified in the CDPATH variable to tab completions for cd, but at the expense of breaking the default completion behavior.
See http://www.gnu.org/software/bash/manual/bashref.html#Programmable-Completion for more gory details.
For the second instance, you can press ESC before tab to solve it.
I don't know the solution to your problem, but you could look in /etc/bash_completion or the files under /etc/bash_completion.d to determine what commands use autocompletion and how.
help complete
Might also be helpful.
The Bash Reference Manual has more information than you might want on expansion errata.
Section 8.7 looks like it would be the place to start. It give information on the 'complete' function, among other things.
Check the answer for
https://superuser.com/questions/434139/urxvt-tab-expand-environment-variables by Dmitry Alexandrov:
This is about direxpand option. $ shopt -s direxpand and $FOO_PATH/ will be expanded by TAB.
I'm answering 4-year-old question! Fantastic!
This is a bash bug/feature which was unintentionally introduced in v4.2, and was unnoticed for a long period of time. This was pointed out by geirha in this tread. Confirmed as unintended feature here
I came across this problem when running Ubuntu at home. At work I have bash-3.00, so I've spent some time browsing around to see what's going on. I wonder if I can 'downgrade'....