Traditionally, vi is an interactive editor. I am hardpressed to imagine a situation where its functionality can not be replaced by sed -- the stream editor -- or a pipeline series of grep, awk, etc... I'd advise avoiding the vi solution though I'm sure it is possible.
Can you be more specific with your data? For example, are you always replacing a character on the third line only or is there a specific pattern that uniquely identifies that line?
Here is a simple example that replaces all lowercase 'e' characters with an uppercase 'E' on line 3 only. Given the following file:
You could then redirect the output to a temporary file, say file.tmp and then move it back to file.
I have the following crontab entry to run a shell script for every 30 minutes of every day:
30 * * * * $HOME/main.sh > $HOME/main.log 2>$HOME/error.log
after I created the crontab file I have also done:
$crontab my_crontab
I also check to make sure it exists, by using the following... (11 Replies)
Hi, need help, I would like to know what is this IF statement trying to do? When the script is executing and error out with line 9 which is the IF statement line.
if ]
then
TOPDIR=$(pwd)
else
TOPDIR=${0%/*}
fi
TOPDIR=${TOPDIR%/*}
the log file.
Current system time is... (15 Replies)
Hi
Script not getting executed via cron but executes successfully when executed manually. Please assist
cbspsap01(appuser) /app/scripts > cat restart.sh
#!/bin/ksh
cd /app/bin
date >>logfile.out
echo "Restart has been started....." >>logfile.out
date >>logfile.out
initfnsw -y restart... (3 Replies)
I made a shell script to execute a server in screen mode.
# start server
screen -d -m -S Test ./application
echo "Program Started Successfully"
than I'm executing it from php by
echo shell_exec('/home/script.sh');
and it is giving me this error.
"cannot make directory... (1 Reply)
Hi,
I am having a shell script which has a while loop as shown below.
while
do
sleep 60
done
I am executing this script from Informatica ETL tool command task from where we can execute UNIX commands/scripts. When i do that, i am seeing 2 processes getting started for one script... (2 Replies)
Hi
As per my requirement when I run . ./file.sh am getting the following error
-bash:ELF: command not found
when i execute as ./file.sh it is getting executed.How to resolve this.
Thanks in advance. (3 Replies)
Hi every one, i am new to shell script. my people given a task to write a shell script that should execute number of shell scripts in that. in that, if any shell script is failed to execute, we have to run the main script again, but the script should start execute from the failed script only..
it... (1 Reply)
Hi every one, i am new to shell script. my people given a task to write a shell script that should execute number of shell scripts in that. in that, if any shell script is failed to execute, we have to run the main script again, but the script should start execute from the failed script only..
it... (6 Replies)
I am able to execute awk command from shell prompt. but the same command is not getting executed when written and run in a bash script
the command from bash cmd prompt.
awk '/world/{for (i=2; i<NF; i++) printf $i " "; print $NF}1' myfile >tmp$$ ; mv tmp$$ myfile
file:
# hello world my... (4 Replies)
I have bash shell script which is internally calling python script.I would like to know how long python is taking to execute.I am not allowed to do changes in python script.Please note i need to know execution time of python script which is getting executed inside shell .I need to store execution... (2 Replies)
Discussion started by: Adfire
2 Replies
LEARN ABOUT LINUX
unbuffer
UNBUFFER(1) General Commands Manual UNBUFFER(1)NAME
unbuffer - unbuffer output
SYNOPSIS
unbuffer program [ args ]
INTRODUCTION
unbuffer disables the output buffering that occurs when program output is redirected from non-interactive programs. For example, suppose
you are watching the output from a fifo by running it through od and then more.
od -c /tmp/fifo | more
You will not see anything until a full page of output has been produced.
You can disable this automatic buffering as follows:
unbuffer od -c /tmp/fifo | more
Normally, unbuffer does not read from stdin. This simplifies use of unbuffer in some situations. To use unbuffer in a pipeline, use the
-p flag. Example:
process1 | unbuffer -p process2 | process3
CAVEATS
unbuffer -p may appear to work incorrectly if a process feeding input to unbuffer exits. Consider:
process1 | unbuffer -p process2 | process3
If process1 exits, process2 may not yet have finished. It is impossible for unbuffer to know long to wait for process2 and process2 may
not ever finish, for example, if it is a filter. For expediency, unbuffer simply exits when it encounters an EOF from either its input or
process2.
In order to have a version of unbuffer that worked in all situations, an oracle would be necessary. If you want an application-specific
solution, workarounds or hand-coded Expect may be more suitable. For example, the following example shows how to allow grep to finish pro-
cessing when the cat before it finishes first. Using cat to feed grep would never require unbuffer in real life. It is merely a place-
holder for some imaginary process that may or may not finish. Similarly, the final cat at the end of the pipeline is also a placeholder
for another process.
$ cat /tmp/abcdef.log | grep abc | cat
abcdef
xxxabc defxxx
$ cat /tmp/abcdef.log | unbuffer grep abc | cat
$ (cat /tmp/abcdef.log ; sleep 1) | unbuffer grep abc | cat
abcdef
xxxabc defxxx
$
BUGS
The man page is longer than the program.
SEE ALSO
"Exploring Expect: A Tcl-Based Toolkit for Automating Interactive Programs" by Don Libes, O'Reilly and Associates, January 1995.
AUTHOR
Don Libes, National Institute of Standards and Technology
1 June 1994 UNBUFFER(1)