I am trying to tail multiple files in a ksh. I have the following script:
test.sh
#!/bin/ksh
for file in "$#"
do
# show tails of each in background.
tail -f $file>out.txt
echo "\n"
done
It is only reading the first file argument I provide to the script. Not reading the other files as the argument to the script.
When I do this:
./test.sh /var/adm/messages /var/adm/logs
it is only reading the /var/adm/messages not the logs. Any ideas what I might be doing wrong
You should use double ">>" syntax to redirect the stream at the end of your output file.
A simple ">" redirection will write the stream at the beginning of the file and consequently it will remove the previous content.
So try :
#!/bin/ksh
for file in "$#"
do
# show tails of each in background.
tail -f $file >> out.txt & # Don't forget to add the last character
done
EDIT : If you want to use multi tail it's not installed by default. On Debian or Ubuntu you can use apt-get install multi tail.
Related
I've got a script on my computer named test.py. What I've been doing so far to run the program is type python test.py into the terminal.
Is there a command on Unix operating systems that doesn't require the user to specify the program he/she uses to run the script but that will instead run the script using whichever program the shebang line is pointing to?
For example, I'm looking for a command that would let me type some_command test.txtinto the terminal, and if the first line of test.txt is #!/usr/bin/python, the script would be interpreted as a python script, but if the first line is #!/path/to/javascript/interpreter, the the script would be interpreted as javascript.
This is the default behavior of the terminal (or just executing a file in general) all you have to do is make the script executable with
chmod u+x test.txt
Then (assuming text.txt is in your current directory) every time you type
./text.txt
It will look at the sh-bang line and use the program there to run text.txt.
If you really want to duplicate built-in functionality, try this.
#!/bin/sh
x=$1
shift
p=$(sed -n 's/^#!//p;q' "$x" | grep .) && exec $p "$#"
exec "$x" "$#"
echo "$0: $x: No can do" >&2
Maybe call it start to remind you of the similarly useful Windows command.
Why tail command -f option does not work well. when target file was null clear, then tail command does not write out anymote.
tail -f hoge&
cp /dev/null hoge
Tail also has a tail -F option which checks to see if the file has been changed.
From the man page:
The -F option implies the -f option, but tail will also check to see
if the file being followed has been renamed or rotated. The file is
closed and reopened when tail detects that the filename being read
from has a new inode number. The -F option is ignored if reading from
standard input rather than a file.
Following html mail using mailx command is working from shell terminal, but the same command is not working from shell script.
mailx -s "$(echo -e "${sub} TRP OF ${system} \nContent-Type: text/html")" example#gmail.com < TRP.html
I guess it is some small escape character error, but not sure what it is.
Can any one help here?
Perhaps your vars sub / system are only known in your current environment.
When your sript is called mymail, try
. mymail
(Start with a dot),
or first export your vars.
When these suggestions fail, debug:
use set -x or temporary put an "echo -e" in front of your line.
Im new to unix,I have search a lot of info but still don not how to make it in a bash
What i know is used this command ls -tr|xargs -i ksh -c "mv {} ../tmp/" to move file by file.
Now I need to make a script that sorts all of these files by system date and moves them into a directory, The first 1000 oldest files being to be moved.
Example files r like these
KPK.AWQ07102011.66.6708.01
KPK.AWQ07102011.68.6708.01
KPK.EER07102011.561.8312.13
KPK.WWS07102011.806.3287.13
-----------This is the script tat i hv been created-------
if [ ! -d /app/RAID/Source_Files/test/testfolder ] then
echo "test directory does not exist!"
mkdir /app/RAID/Source_Files/calvin/testfolder
echo "unused_file directory created!"
fi
echo "Moving xx oldest files to test directory"
ls -tr /app/RAID/Source_Files/test/*.Z|head -1000|xargs -i ksh -c "mv {} /app/RAID/Source_Files/test/testfolder/"
the problem of this script is
1) unix prompt a syntax erro 'if'
2) The move command is working but it create a new filename testfolder instead move to directory testfolder (testfolder alredy been created in this path)
anyone can gv me a hand ? thanks
Could this help?
mv `ls -tr|head -1000` ../tmp/
head -n takes the n first lines of the previous command (here the 1000 oldest files). The backticks allow for the result of ls and head commands to be used as arguments to mv.
I have a script that looks like this
#!/bin/bash
function something() {
echo "hello world!!"
}
something | tee logfile
I have set the execute permission on this file and when I try running the file like this
$./script.sh
it runs perfectly fine, but when I run it on the command line like this
$sh script.sh
It throws up an error. Why does this happen and what are the ways in which I can fix this.
Running it as ./script.sh will make the kernel read the first line (the shebang), and then invoke bash to interpret the script. Running it as sh script.sh uses whatever shell your system defaults sh to (on Ubuntu this is Dash, which is sh-compatible, but doesn't support some of the extra features of Bash).
You can fix it by invoking it as bash script.sh, or if it's your machine you can change /bin/sh to be bash and not whatever it is currently (usually just by symlinking it - rm /bin/sh && ln -s /bin/bash /bin/sh). Or you can just use ./script.sh instead if that's already working ;)
If your shell is indeed dash and you want to modify the script to be compatible, https://wiki.ubuntu.com/DashAsBinSh has a helpful guide to the differences. In your sample it looks like you'd just have to remove the function keyword.
if your script is at your present working directory and you issue ./script.sh, the kernel will read the shebang (first line) and execute the shell interpreter that is defined. you can also call your script.sh by specifying the path of the interpreter eg
/bin/bash myscript.sh
/bin/sh myscript.sh
/bin/ksh myscript.sh etc
By the way, you can also put your shebang like this (if you don't want to specify full path)
#!/usr/bin/env sh
sh script.sh forces the script to be executed within the sh - shell.
while simply starting it from command line uses the shell-environemnt you're in.
Please post the error message for further answers.
Random though on what the error may be:
path specified in first line /bin/bash is wrong -- maybe bash is not installed?