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Is it possible to get, using Bash, a list of commands starting with a certain string?
I would like to get what is printed hitting <tab> twice after typing the start of the command and, for example, store it inside a variable.
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Example-2: Iterating a string variable using for loopCreate a bash file named 'for_list2.sh' and add the following script. Assign a text into the variable, StringVal and read the value of this variable using for loop.
Dollar sign $ (Variable) The dollar sign before the thing in parenthesis usually refers to a variable. This means that this command is either passing an argument to that variable from a bash script or is getting the value of that variable for something.
$_ (dollar underscore) is another special bash parameter and used to reference the absolute file name of the shell or bash script which is being executed as specified in the argument list. This bash parameter is also used to hold the name of mail file while checking emails.
In bash, ksh or zsh, typeset -f lists functions with their definitions. In bash, you can list all command names of any type with compgen -c. You can use compgen -A alias, compgen -A builtin compgen -A function to list commands of a specific type. You can pass an additional string to compgen to list only commands that start with that prefix.
Bash check if string starts with character using if statement if..else..fi allows to make choice based on the success or failure of a command: #!/bin/bash input = "xBus" if then echo "Start with B" else echo "No match" fi Bash check if a variable string begins with # value
Bash String is a data type similar to integer or boolean. It is generally used to represent text. It is a string of characters that may also contain numbers enclosed within double or single quotes. Example: “geeksforgeeks”, “Geeks for Geeks” or “23690” are strings
Type Ctrl R and then type part of the command you want. Bash will display the first matching command. Keep typing Ctrl R and bash will cycle through previous matching commands. To search backwards in the history, type Ctrl S instead.
You should be able to use the compgen command, like so:
compgen -A builtin [YOUR STRING HERE]
For example, "compgen -A builtin l" returns
let
local
logout
You can use other keywords in place of "builtin" to get other types of completion. Builtin gives you shell builtin commands. "File" gives you local filenames, etc.
Here's a list of actions (from the BASH man page for complete which uses compgen):
alias Alias names. May also be specified as -a.
arrayvar Array variable names.
binding Readline key binding names.
builtin Names of shell builtin commands. May also be specified as -b.
command Command names. May also be specified as -c.
directory Directory names. May also be specified as -d.
disabled Names of disabled shell builtins.
enabled Names of enabled shell builtins.
export Names of exported shell variables. May also be specified as -e.
file File names. May also be specified as -f.
function Names of shell functions.
group Group names. May also be specified as -g.
helptopic Help topics as accepted by the help builtin.
hostname Hostnames, as taken from the file specified by the HOSTFILE shell
variable.
job Job names, if job control is active. May also be specified as
-j.
keyword Shell reserved words. May also be specified as -k.
running Names of running jobs, if job control is active.
service Service names. May also be specified as -s.
setopt Valid arguments for the -o option to the set builtin.
shopt Shell option names as accepted by the shopt builtin.
signal Signal names.
stopped Names of stopped jobs, if job control is active.
user User names. May also be specified as -u.
variable Names of all shell variables. May also be specified as -v.
A fun way to do this is to hit M-* (Meta is usually left Alt).
As an example, type this:
$ lo
Then hit M-*:
$ loadkeys loadunimap local locale localedef locale-gen locate
lockfile-create lockfile-remove lockfile-touch logd logger login
logname logout logprof logrotate logsave look lorder losetup
You can read more about this in man 3 readline; it's a feature of the readline library.
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