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Full Discussion: Simple maths calculator loop.
Top Forums Shell Programming and Scripting Simple maths calculator loop. Post 302583054 by agama on Monday 19th of December 2011 12:21:36 PM
Old 12-19-2011
Here are a couple of examples that should illustrate enough to get you going. You should be able to figure out how to 'plug' your code into a loop like one of these:

Code:
#!/usr/bin/env ksh

# simple loop examples
# this will work in both bash and kshell
buf="x"                         # seed to enter loop
while [[ -n $buf  ]]            # until they enter an empty buffer
do
    printf "enter a string or nothing to quit: "        # prompt
    read buf
    if [[ -n $buf ]]
    then
        printf "${buf//[aeiou]/}\n"                     # do something with valid input
    fi
done


# this illustrates a different technique, the prompt will only work in kshell
# the two command prompting mechanism from the previous example can 
# be substituted for portability. 
while true          # forever
do
    read buf?"enter a string or nothing to quit: "  # prompt and read user input
    if [[ -z $buf  ]]        # also (silently) support end of file
    then
        printf "\n"         # if they used ^D ensure prompt is on next line
        exit 0
    fi

    printf "${buf//[aeiou]/}\n"     # do something with user input and print
done                # loop for more

 

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LEARN ABOUT CENTOS

ui_compat

ui_compat(3)							      OpenSSL							      ui_compat(3)

NAME

       des_read_password, des_read_2passwords, des_read_pw_string, des_read_pw - Compatibility user interface functions

SYNOPSIS

	#include <openssl/des_old.h>

	int des_read_password(DES_cblock *key,const char *prompt,int verify);
	int des_read_2passwords(DES_cblock *key1,DES_cblock *key2,
	       const char *prompt,int verify);

	int des_read_pw_string(char *buf,int length,const char *prompt,int verify);
	int des_read_pw(char *buf,char *buff,int size,const char *prompt,int verify);

DESCRIPTION

       The DES library contained a few routines to prompt for passwords.  These aren't necessarely dependent on DES, and have therefore become
       part of the UI compatibility library.

       des_read_pw() writes the string specified by prompt to standard output turns echo off and reads an input string from the terminal.  The
       string is returned in buf, which must have spac for at least size bytes.  If verify is set, the user is asked for the password twice and
       unless the two copies match, an error is returned.  The second password is stored in buff, which must therefore also be at least size
       bytes.  A return code of -1 indicates a system error, 1 failure due to use interaction, and 0 is success.  All other functions described
       here use des_read_pw() to do the work.

       des_read_pw_string() is a variant of des_read_pw() that provides a buffer for you if verify is set.

       des_read_password() calls des_read_pw() and converts the password to a DES key by calling DES_string_to_key(); des_read_2password()
       operates in the same way as des_read_password() except that it generates two keys by using the DES_string_to_2key() function.

NOTES

       des_read_pw_string() is available in the MIT Kerberos library as well, and is also available under the name EVP_read_pw_string().

SEE ALSO

       ui(3), ui_create(3)

AUTHOR

       Richard Levitte (richard@levitte.org) for the OpenSSL project (http://www.openssl.org).

1.0.1e								    2013-02-11							      ui_compat(3)
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