Hi jejemonx...
This is what vbe was referring to assuming you are using 'bash':
AND, an example of how it works:
As you can see whether you input variables 'b' and 'c' or not they have 'NULL' values so there will always be 3 variables.
You could always use 3 separate 'read's and check each one for validity and restart the loop as required if one or more is not a number...
I need the date validation. I searched in the google but i didn't find my requirements.
requirements:
1) user has to enter the date in YYYY/MM/DD format
2) MM validations
3) DD validations.
and if the month is april it should allow 30 days only and for May month it should allow 31 days like... (1 Reply)
Hello everyone!
I am a bit inexperienced with administering queueing programs. I installed Torque (a PBS derivative) on a Linux cluster and it is running well. There is one annoying problem though: users can run massively parallel jobs and serial jobs too. Almost all users do a mix of the two. I... (0 Replies)
Hi i am a total noob at shell scripting. i was wondering if somebody could help me with my script.
i want the script to search the dev folder for the burner file
because they are different between distrubutions? as i under stand it.
this i the script.
#!/bin/bash
echo "Script för att bränna 360... (4 Replies)
ok the user can only enter a number if a letter is entered it shouldnt be accepted
This is what i have so far
read -p "How many cars to enter:" cars
until
do
read -p "Invalid number. Please re-enter:" $tags
done (5 Replies)
Hello
Does the unix korn shell provide a function to convert number entered in command line argument to text or Character so that in next step i will convert Chr to Hex (6 Replies)
Hello,
I am new to awk and I am trying to figure out how to print an output based on user input.
For example:
ubuntu:~/scripts$ steps="step1, step2, step3"
ubuntu:~/scripts$ echo $steps
step1, step2, step3
I am playing around and I got this pattern that I want:
... (3 Replies)
Hi Experts,
path=/db/files/
format=$1
User can enter any file format.compare the user file format with actual file format existed in the directory /db/files. User enter all characters as "A" apart from date format.
example1: user will be entering the file format AAA_AA_YYYYMMDD.AAA
Actual... (6 Replies)
Hello All,
I have a file of ip addresses called activeips.txt
What I'm trying to do is run a simple bash script that has a loop in it. The loop is a cat of the IP addresses in the file.
The goal is to run 2 nmap commands to give me outputs where each address in the list has an OS... (11 Replies)
Discussion started by: Dirk_Pitt
11 Replies
LEARN ABOUT X11R4
read
read(1) User Commands read(1)NAME
read - read a line from standard input
SYNOPSIS
/usr/bin/read [-r] var...
sh
read name...
csh
set variable = $<
ksh
read [ -prsu [n]] [ name ? prompt] [name...]
DESCRIPTION
/usr/bin/read
The read utility will read a single line from standard input.
By default, unless the -r option is specified, backslash () acts as an escape character. If standard input is a terminal device and the
invoking shell is interactive, read will prompt for a continuation line when:
o The shell reads an input line ending with a backslash, unless the -r option is specified.
o A here-document is not terminated after a NEWLINE character is entered.
The line will be split into fields as in the shell. The first field will be assigned to the first variable var, the second field to the
second variable var, and so forth. If there are fewer var operands specified than there are fields, the leftover fields and their interven-
ing separators will be assigned to the last var. If there are fewer fields than vars, the remaining vars will be set to empty strings.
The setting of variables specified by the var operands will affect the current shell execution environment. If it is called in a subshell
or separate utility execution environment, such as one of the following:
(read foo)
nohup read ...
find . -exec read ... ;
it will not affect the shell variables in the caller's environment.
The standard input must be a text file.
sh
One line is read from the standard input and, using the internal field separator, IFS (normally space or tab), to delimit word boundaries,
the first word is assigned to the first name, the second word to the second name, and so on, with leftover words assigned to the last name.
Lines can be continued using
ewline. Characters other than NEWLINE can be quoted by preceding them with a backslash. These backslashes
are removed before words are assigned to names, and no interpretation is done on the character that follows the backslash. The return code
is 0, unless an end-of-file is encountered.
csh
The notation:
set variable = $<
loads one line of standard input as the value for variable. (See csh(1)).
ksh
The shell input mechanism. One line is read and is broken up into fields using the characters in IFS as separators. The escape character,
(), is used to remove any special meaning for the next character and for line continuation. In raw mode, -r, the character is not
treated specially. The first field is assigned to the first name, the second field to the second name, and so on, with leftover fields
assigned to the last name. The -p option causes the input line to be taken from the input pipe of a process spawned by the shell using |&.
If the -s flag is present, the input will be saved as a command in the history file. The flag -u can be used to specify a one digit file
descriptor unit n to read from. The file descriptor can be opened with the exec special command. The default value of n is 0. If name is
omitted, REPLY is used as the default name. The exit status is 0 unless the input file is not open for reading or an end-of-file is encoun-
tered. An end-of-file with the -p option causes cleanup for this process so that another can be spawned. If the first argument contains a
?, the remainder of this word is used as a prompt on standard error when the shell is interactive. The exit status is 0 unless an end-of-
file is encountered.
OPTIONS
The following option is supported:
-r Does not treat a backslash character in any special way. Considers each backslash to be part of the input line.
OPERANDS
The following operand is supported:
var The name of an existing or non-existing shell variable.
EXAMPLES
Example 1: An example of the read command
The following example for /usr/bin/read prints a file with the first field of each line moved to the end of the line:
example% while read -r xx yy
do
printf "%s %s
" "$yy" "$xx"
done < input_file
ENVIRONMENT VARIABLES
See environ(5) for descriptions of the following environment variables that affect the execution of read: LANG, LC_ALL, LC_CTYPE, LC_MES-
SAGES, and NLSPATH.
IFS Determines the internal field separators used to delimit fields.
PS2 Provides the prompt string that an interactive shell will write to standard error when a line ending with a backslash is read and
the -r option was not specified, or if a here-document is not terminated after a newline character is entered.
EXIT STATUS
The following exit values are returned:
0 Successful completion.
>0 End-of-file was detected or an error occurred.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
+-----------------------------+-----------------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+-----------------------------+-----------------------------+
|Availability |SUNWcsu |
+-----------------------------+-----------------------------+
|Interface Stability |Standard |
+-----------------------------+-----------------------------+
SEE ALSO csh(1), ksh(1), line(1), set(1), sh(1), attributes(5), environ(5), standards(5)SunOS 5.10 28 Mar 1995 read(1)