Sponsored Content
Top Forums UNIX for Dummies Questions & Answers When do I use input redirection? Post 302857703 by Don Cragun on Friday 27th of September 2013 02:56:15 AM
Old 09-27-2013
Quote:
Originally Posted by PTcharger
Can someone please explain when input redirection is necessary?

For example, "cat filename" and "cat< filename" produce the same result. I was told that if I need to bunzip a file that I should type "bunzip2<filename.bz2." However, if I omit the "<" I still get the same result. Can someone please give me a situation or command which requires input redirection?
Try the following:
Code:
tr -d " " < file

or:
Code:
i=0
while read x1 x2 x3
do      printf "Line%2d: %s\n" $((++i)) "$x2"
done < file

when file contains:
Code:
abc def ghi jkl
123 456 7
Last input line

 

10 More Discussions You Might Find Interesting

1. UNIX for Dummies Questions & Answers

Input Redirection

Hi everybody, first of all i am a new member in UNIX.com and this is my first post. I am impressed with the amount of information a person can ever have in this forum, it is really great having something similiar; anyways let me tell you about the problem I am having, hope you will answer me.... (6 Replies)
Discussion started by: majeed73
6 Replies

2. Shell Programming and Scripting

input redirection question

Hi, in my script I need to execute the following command: query $id 456 432 but it waits for a RETURN character from keyboard and therefore, it fails. I tried something like: query $id 456 432 << '\n' but, i'ts clear it is not correct. Is there any way to do this? Thxs. (0 Replies)
Discussion started by: luistid
0 Replies

3. Shell Programming and Scripting

permanent redirection of standard input

while running a user inter-active program how can we get the commands from a file instead of the user? is there anyway to permanently redirect content of a file to standard input? (6 Replies)
Discussion started by: gfhgfnhhn
6 Replies

4. UNIX for Advanced & Expert Users

password required when using input redirection

Hello, I need to change user and run some commands by using a script. lets say, I'm using su - someuser << start password required -----> how can I enter the password here command 1 command 2 command 3 command 4 start While trying to run this I got the following message: "standard... (2 Replies)
Discussion started by: Alalush
2 Replies

5. Shell Programming and Scripting

Input redirection and for loop

Hello, I need help with a bash script that I try to improve. I could not find answer so far, maybe because I'm not to familiar with the terminology so feel free to correct my language. I have a script that looks like: NODES="node_a node_b node_c" for NODE in $NODES do ... (4 Replies)
Discussion started by: pn8830
4 Replies

6. Shell Programming and Scripting

How to check for Input Redirection in my script?

All, I have a requirement to write a script where I check for Input redirection when the script was executed, based on which I handle my logic. Below is the example: my.script #! /bin/ksh # Not sure how to frame the if condition below if ; then echo "Input Redirected from a file" ... (7 Replies)
Discussion started by: bharath.gct
7 Replies

7. UNIX for Dummies Questions & Answers

Send job to Background after input redirection

Hi, I am having issues with syntax when I am trying to send a job to the background after a input redirection. I have this script which sends some files to different servers after zipping them. Once I execute it, it will ask for user input as of which server the files need to go to. (The... (3 Replies)
Discussion started by: grep_me
3 Replies

8. UNIX for Dummies Questions & Answers

Redirection of file input to command

Hello, I'm new to Unix (working with OS X 10.8.5) and therefore at the beginning of my adventure. If I ask something stupid, then this is not intentional, but simple nescience. :rolleyes: I have a problem with the redirection of text file content to echo. I was experimenting with redirection... (6 Replies)
Discussion started by: pseudo
6 Replies

9. Shell Programming and Scripting

Input redirection script

Hi, #!/bin/bash while ; do rm -f /tmp/pipe mkfifo /tmp/pipe ./yuv4mpeg_to_v4l2 < /tmp/pipe & mplayer tom_and_jerry.mp4 -vf scale=480:360 -vo yuv4mpeg:file=/tmp/pipe sleep 65; done When I run this - after mplayer finishes playing video it says - Exiting... (End of... (2 Replies)
Discussion started by: ashokvpp
2 Replies

10. Shell Programming and Scripting

Input redirection within bash script

Hi, when I try to redirect input and the command is described as a string within an array redirection does not work. why? #!/bin/bash dir=("tail < ./hello.txt") tail < ./hello.txt #works ${dir} #does not work (2 Replies)
Discussion started by: heinzel
2 Replies
BZEXE(1)						      General Commands Manual							  BZEXE(1)

NAME
bzexe - compress executable files in place SYNOPSIS
bzexe [ name ... ] DESCRIPTION
The bzexe utility allows you to compress executables in place and have them automatically uncompress and execute when you run them (at a penalty in performance). For example if you execute ``bzexe /bin/cat'' it will create the following two files: -r-xr-xr-x 1 root bin 9644 Feb 11 11:16 /bin/cat -r-xr-xr-x 1 bin bin 24576 Nov 23 13:21 /bin/cat~ /bin/cat~ is the original file and /bin/cat is the self-uncompressing executable file. You can remove /bin/cat~ once you are sure that /bin/cat works properly. This utility is most useful on systems with very small disks. OPTIONS
-d Decompress the given executables instead of compressing them. SEE ALSO
bzip2(1), znew(1), zmore(1), zcmp(1), zforce(1) CAVEATS
The compressed executable is a shell script. This may create some security holes. In particular, the compressed executable relies on the PATH environment variable to find gzip and some other utilities (tail, chmod, ln, sleep). BUGS
bzexe attempts to retain the original file attributes on the compressed executable, but you may have to fix them manually in some cases, using chmod or chown. BZEXE(1)
All times are GMT -4. The time now is 02:50 AM.
Unix & Linux Forums Content Copyright 1993-2022. All Rights Reserved.
Privacy Policy