I have a chain of commands that can execute all at once, however I wish to put it inside of a bash script. The problem is that I have no clue how to. My command is like so:
/usr/bin/sort -n db | /usr/bin/awk -F: '{print $1; print $2}' | db5.1_load -T -t hash newdb
How can I convert the above into a bash script?
This should normally be as simple as putting the shell command into a text file, and putting the Unix shebang on the first line of the file, which defines which program to use to run the script (in this case, /bin/bash). So this would look like:
#!/bin/bash
/usr/bin/sort -n db | /usr/bin/awk -F: '{print $1; print $2}' | db5.1_load -T -t hash newdb
Related
This question already has answers here:
How to pass parameters to a Bash script?
(4 answers)
Closed 1 year ago.
At the beginning I have a file.txt, which contains several informations that I will take using the grep command as you see in the script.
What I want is to give the script the file I want instead of file.txt but without changing the file name each time in the script for example if the file is named Me.txt I don’t want to go into the script and write Me.txt in each grep command especially if I have dozens of orders.
Is there a way to do this?
#!/bin/bash
grep teste file.txt > testline.txt
awk '{print $2}' testline.txt > test.txt
echo '#'
echo '#'
grep remote file.txt > remoteline.txt
awk '{print $3}' remoteline.txt > remote.txt
echo '#'
echo '#'
grep adresse file.txt > adresseline.txt
awk '{print $2}' adresseline.txt > adresse.txt
Using a parameter, as many contributors here suggested, is of course the obvious approach, and the one which is usually taken in such case, so I want to extend this idea:
If you do it naively as
filename=$1
you have to supply the name on every invocation. You can improve on this by providing a default value for the case the parameter is missing:
filename=${1:-file.txt}
But sometimes you are in a situation, where for some time (working on a specific task), you always need the same filename over and over, and the default value happens to be not the one you need. Another possibility to pass information to a program is via the environment. If you set the filename by
filename=${MOOFOO:-file.txt}
it means that - assuming your script is called myscript.sh - if you invoke your script by
MOOFOO=myfile.txt myscript.sh
it uses myfile.txt, while if you call it by
myscript.sh
it uses the default file.txt. You can also set MOOFOO in your shell, as
export MOOFOO=myfile.txt
and then, even a lone execution of
myscript.sh
with use myfile.txt instead of the default file.txt
The most flexible approach is to combine both, and this is what I often do in such a situation. If you do in your script a
filename=${1:-${MOOFOO:-file.txt}}
it takes the name from the 1st parameter, but if there is no parameter, takes it from the variable MOOFOO, and if this variable is also undefined, uses file.txt as the last fallback.
You should pass the filename as a command line parameter so that you can call your script like so:
script <filename>
Inside the script, you can access the command line parameters in the variables $1, $2,.... The variable $# contains the number of command line parameters passed to the script, and the variable $0 contains the path of the script itself.
As with all variables, you can choose to put the variable name in curly brackets which has advantages sometimes: ${1}, ${2}, ...
#!/bin/bash
if [ $# = 1 ]; then
filename=${1}
else
echo "USAGE: $(basename ${0}) <filename>"
exit 1
fi
grep teste "${filename}" > testline.txt
awk '{print $2}' testline.txt > test.txt
echo '#'
echo '#'
grep remote "${filename}" > remoteline.txt
awk '{print $3}' remoteline.txt > remote.txt
echo '#'
echo '#'
grep adresse "${filename}" > adresseline.txt
awk '{print $2}' adresseline.txt > adresse.txt
By the way, you don't need two different files to achieve what you want, you can just pipe the output of grep straight into awk, e.g.:
grep teste "${filename}" | awk '{print $2}' > test.txt
but then again, awk can do the regex match itself, reducing it all to just one command:
awk '/teste/ {print $2}' "${filename}" > test.txt
I want to use tail in my custom pipe command.
For example, I want to execute this command:
>ls -1 | tail -n 1 | awk '{print "last file is "$1}'
>last file is test.txt
And I want to make it short by making my own custom script. It looks like this:
>ls -1 | myscript
>last file is test.txt
I know myscript can get input from "ls -1" by this code:
while read line; do
echo last file is $line
done
But I don't know how to use "tail -n 1" in the custom pipe command code above.
Is there a way to use a pipe command in another pipe command script?
Or do I have to implement the code which does the same process as "tail -n 1" myself?
I hope bash has some solution for this.
Try putting just this in myscript
tail -n 1 | awk '{print "last file is "$1}'
This works as the first command (tail) consumes the stdin of your script. In general, scripts work as though you typed their contest as-is to the terminal.
Is there a way to process 2 different files passed as arguments to a bash script which uses awk.
Script signature:
./statistical_sig.sh path_to_reviews_folder hotel_1 hotel_2
I tried the following but only the first argument got processed.
hotel1="$2";
hotel2="$3";
dos2unix -U $hotel1 | dos2unix -U $hotel2 | echo "$hotel1" "$hotel2" | xargs | awk -v hotel1="$hotel1" -v hotel2="$hotel2" { .. code ..}
You don't need all these pipes to run awk.
Either you will use something like this if you plan to read with awk some other files and use hotel1 and hotel2 somehow inside your awk code:
awk -v hotel1=$(dos2unix -U "$hotel1") -v hotel2=$(dos2unix -U "$hotel2") { awk code ..} file1 file2
Or you will use this if you plan to read and process contents of files hotel1 and hotel2:
awk { awk code ..} <(dos2unix -U "$hotel1") <(dos2unix -U "$hotel2")
Alternativelly you can modify your code like this, but this is less efficient :
hotel1=$(dos2unix "$hotel1") && hotel2=$(dos2unix "$hotel2") && echo "$hotel1 $hotel2" | awk '{your code here}'
If you explain better your question advising what is the awk code and what you are trying to achieve, you will get better advises.
I have to run many python script which differ just with one parameter. I name them as runv1.py, runv2.py, runv20.py. I have the original script, say runv1.py. Then I make all copies that I need by
cat runv1.py | tee runv{2..20..1}.py
So I have runv1.py,.., runv20.py. But still the parameter v=1 in all of them.
Q: how can I also replace v parameter to read it from the file name? so e.g in runv4.py then v=4. I would like to know if there is any one-line shell command or combination of commands. Thank you!
PS: direct editing each file is not a proper solution when there are too many files.
Below for loop will serve your purpose I think
for i in `ls | grep "runv[0-9][0-9]*.py"`
do
l=`echo $i | tr -d [a-z.]`
sed -i 's/v/'"$l"'/g' runv$l.py
done
Below command was to pass the parameter to script extracted from the filename itself
ls | grep "runv[0-9][0-9]*.py" | tr -d [a-z.] | awk '{print "./runv"$0".py "$0}' | xargs sh
in the end instead of sh you can use python or bash or ksh.
I run an xargs command invoking bash shell with multiple commands. I am unable to figure out how to print two columns with different delimiters.
The command is ran is below
cd /etc/yp
cat "$userlist" | xargs -I {} bash -c "echo -e 'For user {} \n'
grep -w {} auto_*home|sed 's/:/ /' | awk '{print \$1'\t'\$NF}'
grep -w {} passwd group netgroup |cut -f1 -d ':'|sort|uniq;echo -e '\n'"
the output I get is
For user xyz
auto_homeabc.jkl.com:/rtw2kop/xyz
group
netgroup
passwd
I need a tab after the auto_home(since it is a filename) like in
auto_home abc.jkl.com:/rtw2kop/xyz
The entry from auto_home file is below
xyz -rw,intr,hard,rsize=32768,wsize=32768 abc.jkl.com:/rtw2kop/xyz
How do I awk for the first field(auto_home) and the last field abc.jkl.com:/rtw2kop/xyz? As I have put a pipe from grep command to awk.'\t' isnt working in the above awk command.
If I understand what you are attempting correctly, then I suggest this approach:
while read user; do
echo "For user $user"
awk -v user="$user" '$1 == user { print FILENAME "\t" $NF }' auto_home
awk -F: -v user="$user" '$1 == user { print FILENAME; exit }' passwd group netgroup | sort -u
done < "$userlist"
The basic trick is the read loop, which will read a line into the variable $user from the file named in $userlist; after that, it's all straightforward awk.
I took the liberty of changing the selection criteria slightly; it looked as though you wanted to select for usernames, not strings anywhere in the line. This way, only lines will be selected in which the first token is equal to the currently inspected user, and lines in which other tokens are equal to the username but not the first are discarded. I believe this to be what you want; if it is not, please comment and we can work it out.
In the 1st awk command, double-escape the \t to \\t. (You may also need to double-escape the \n.)