CODEWITHSUNDEEP
bash
Wizard
Wizard

Reputation: 22113

Reference options of `read` on the command line

I am learning read command,
there are multiple options including -p, -e, -i,
For instance:

    if read -t 10 -sp "Enter secret passphrase > " secret_pass; then
        echo -e  "\nSecret passphrase = 'secret_pass'"
    else
        echo -e  "\nInput timed out" >&2
        exit 1
    fi

However, I cannot locate the options from commmand line

    $ man read | grep -e '-e' -e '-p'
    #it return nothing.

Additionally I checked BSD official and failed to find the options. read(2)

How to check them from command line?

Upvotes: 0

Views: 133

Answers (2)

Armali
Armali

Reputation: 19395

How to check them from command line?

It's easiest with nautical's suggestion help read, provided that your command line shell is bash, or bash -c 'help read' in case your command line shell is some other kind of shell.

If you want to read the manual section rather than the help text, you could use:

man bash | more +/'read *\['

man cd shows its BSD builtins, help cd shows it's GNU bash builtin, version 4.4.19(1).When I cd dir in command line, whose builtin is working?

The built-in command of the used shell is executed. If unsure which shell it is, enter echo $0.

Upvotes: 1

user4918296
user4918296

Reputation:

The command read is a shell built-in. You can either check the manual for Bash

man bash

and search for read or you can type

help read

in a Bash shell.

UPDATE

Your follow up question from the comments:

Bash will use its builtin function first. If there is also an executable on your system, which you want to use instead, then you will have to call it by its full path, e.g.,

$ echo Hello # This calls Bash's version of echo
$ /usr/bin/echo World # This calls echo that was installed with the OS

This applies to all commands that exist as executable on the system and also have a builtin counterpart. I am not familiar with BSD but on Linux there is no cd executable. This would mean that a program can change Bash's working directory from outside. I do not know why BSD has such a program and if Bash would even allow it to change its working directory.

Upvotes: 3

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