Help with Bash piped while-read and a read user input at the same time


 
Thread Tools Search this Thread
Top Forums Shell Programming and Scripting Help with Bash piped while-read and a read user input at the same time
# 1  
Old 02-23-2012
Help with Bash piped while-read and a read user input at the same time

Hi
I am new to writing script and want to use a Bash Piped while-read and read from user input.

if something happens on server.log then do while loop or if something happend on user input then do while loop.

Pseudocode something like:
tail -n 3 -f server.log | while read serverline || read -p # -e promptline
do
if something happend on promptline then do this
if something happend serverline then do this

I appreciate all help.
Thanks
# 2  
Old 02-23-2012
Read user input from /dev/tty, to avoid accidentally reading input from the pipe or file instead. /dev/tty will always be the current terminal, if any.

Code:
... | while read LINE
do
        printf "prompt: "
        read USERINPUT </dev/tty
done

These 2 Users Gave Thanks to Corona688 For This Post:
# 3  
Old 02-23-2012
Thanks, will this lock the while loop and wait for user input? I want the script to react and run the wile loop if something happens in the server.log file as well.

Quote:
Originally Posted by Corona688
Read user input from /dev/tty, to avoid accidentally reading input from the pipe or file instead. /dev/tty will always be the current terminal, if any.

Code:
... | while read LINE
do
        printf "prompt: "
        read USERINPUT </dev/tty
done

# 4  
Old 02-23-2012
Yes, it will block.

Since it's bash, you could have it time out eventually if the user doesn't type anything ( read -t 1 userinput < /dev/tty )
This User Gave Thanks to Corona688 For This Post:
# 5  
Old 02-23-2012
I can not get it to work as it builds on that it comes data on file 'server.log' for the program to get to the prompt and there is no steady stream of data on that file.
Quote:
Originally Posted by Corona688
Yes, it will block.

Since it's bash, you could have it time out eventually if the user doesn't type anything ( read -t 1 userinput < /dev/tty )
# 6  
Old 02-24-2012
I don't think I really understand what you're trying to do, then. Could you give a little pseudocode?
This User Gave Thanks to Corona688 For This Post:
# 7  
Old 02-24-2012
No worries, I explain in greater detail. It might very well be that I do not understand you.
I have a process A that depends on two processes.
Process B is the one assigned to the file server.log
Process C is if a user writes something

If data comes from B or C should process A run
Pseudocode something like:
Code:
tail -n 3 -f server.log | while read serverline || read userinput
do
if something happend on userinput then do this
if something happend serverline then do this

I do not know how to write something like this:
Code:
tail -n 3 -f server.log | while read serverline | while read -t 1 userinput < /dev/tty

A problem with another solution like this is that it is locked on the tail line
Code:
tail -n 3 -f server.log | while read serverline
do
        printf "prompt: "
        read -t 1 USERINPUT </dev/tty

And the same problem with a solution like this is that it is locked on the tail line
Code:
do
        printf "prompt: "
        read -t 1 USERINPUT </dev/tty
        tail -n 3 -f server.log | while read serverline
        do

I hope I explained my problem better and if not do not hesitate to ask again.
Login or Register to Ask a Question

Previous Thread | Next Thread

10 More Discussions You Might Find Interesting

1. Shell Programming and Scripting

Unable to read user input inside a loop

Hi, This query is a part of a much more lengthy script. I wish to look for all the files in a folder named "data" which in this case has two files i.e. plan.war and agent.properties. For all the files found under data I wish to ask the user as to where they wish copy the files to. Below,... (14 Replies)
Discussion started by: mohtashims
14 Replies

2. Shell Programming and Scripting

Shell read command is not waiting for user input

Hi, i am working on one automation , for that i have writing one shell program that take user input in "while read line" block. but read command is taking value that is readed by While block. while read line; do command 1; command 2 echo -n "Do you want to continute > " read rsp... (2 Replies)
Discussion started by: ranvijaidba
2 Replies

3. Shell Programming and Scripting

Perl to read user input

I am creating a bash that uses perl . The below code closes before the input is entered. If I run the perl as a .pl it is fine. What am I doing wrong? Thank you :). #!/bin/bash cd 'C:\Users\cmccabe\Desktop\wget' wget -O getCSV.txt http://xxx.xx.xxx.xxx/data/getCSV.csv print... (4 Replies)
Discussion started by: cmccabe
4 Replies

4. Shell Programming and Scripting

BASH - read does not wait for user input in some circumstances

Hello. I am running 2 scripts : script_1 and script_2 These scripts are run as root Script 2 contains : #!/bin/bash # # ~/bin/script_2 # E_BAD_PARAM=115 # date2stamp () { date --date "$1" +%Y-%m-%d___%H:%M:%S } # USER_NAME=$1 NB_PARAM=$# PARAM0=$0 (2 Replies)
Discussion started by: jcdole
2 Replies

5. Shell Programming and Scripting

Using read to prompt for editable user input in Bash 3

Below is a simple script to prompt for user input while suggesting an editable default value at the prompt: shortname=user1 read -e -i $shortname -p "Please enter the username you would like to add: " input USERNAME="${input:-$shortname}" Please enter the username you would like to add:... (3 Replies)
Discussion started by: woodson2
3 Replies

6. Shell Programming and Scripting

Solaris- Read command from user input

I need to write a bourne shell script (solaris 10) that accepts input from the user. The input will be a command- any command like ls/ pwd/ mv etc. After the input is read, the shell must execute the command supplied by the user. I know we use read to play with user inputs. Just not sure how to... (2 Replies)
Discussion started by: PDManc
2 Replies

7. AIX

Read input data within a specified period of time

Hi All, I am working on a script which requires an input from user within one 1 min. So if the user gives the required input within 1 min., it will execute on the basis of input provided by the user.Other wise it will execute on a default value(hard coded inside the script). Now, I am... (19 Replies)
Discussion started by: rajsharma
19 Replies

8. Shell Programming and Scripting

BASH - read use a path as input

I am trying to script simply data transfer. I would like to have the user input the source "SRC" (/Volumes/DriveName/Users/johnq123) and then name the directory that the copied information will go to, "DST" . put I can't get it to work - #!/bin/bash ... (8 Replies)
Discussion started by: dropkick888
8 Replies

9. UNIX for Dummies Questions & Answers

How to read a line of text from user input?

Hiii I wanna a read a line of text from standard input. The user enter data like this way name phone_no month1_salary month2_salary that is user enter the name ,phone no and salary of 2 months in a single line by giving spaces. I wanna add the 3rd and 4th fields ...ie add both... (4 Replies)
Discussion started by: krishnampkkm
4 Replies

10. UNIX for Dummies Questions & Answers

getline to read input from a user

Hi, The gcc compiler has warned about using gets(), so I've been trying my hand at getline. Problem is that I've been able to read from a file, but what I really need is to read from a user's input. I want to use getline like a scanf() command, but I can't figure what to substitute for the fp... (6 Replies)
Discussion started by: sdsd
6 Replies
Login or Register to Ask a Question