This is the bash script.
Counter.sh:
#!/bin/bash
rm -rf home/pi/temp.mp3
cd /home/pi/
now=$(date +"%d-%b-%Y")
count="countshift1.sh"
mkdir $(date '+%d-%b-%Y')
On row 5 of this script, the count variable... I just want to know how to use AWK to change the integer 1 (the 18th character, thanks for the response) into a 3 and then save the Counter.sh file.
This is basically http://mywiki.wooledge.org/BashFAQ/050 -- assuming your script actually does something with $count somewhere further down, you should probably refactor that to avoid this antipattern. See the linked FAQ for much more on this topic.
Having said that, it's not hard to do what you are asking here without making changes to live code. Consider something like
awk 'END { print 5 }' /dev/null > file
in a cron job or similar (using Awk just because your question asks for it, not because it's the best tool for this job) and then in your main script, using that file;
read index <file
count="countshift$index.sh"
While this superficially removes the requirement to change the script on the fly (which is a big win) you still have another pesky problem (code in a variable!), and you should probably find a better way to solve it.
I don't think awk is the ideal tool for that. There are many ways to do it.
I would use Perl.
perl -pi -e 's/countshift1/countshift3/' Counter.sh
Related
I'm storing commands in a file to be read and run line by line by a POSIX shell program. It looks something like this:
curl -fLo $HOME/.antigen.zsh git.io/antigen
curl -fLo $HOME/.vim/autoload/plug.vim --create-dirs https://raw.githubusercontent.com/junegunn/vim-plug/master/plug.vim
vim +"so $HOME/.vimrc" +PlugInstall +qa!
I'm also using this small function body to go through it and run every line:
while read -r line; do
$line
done < file
Simple stuff. And it works! However, I am having trouble expanding $HOME to my home directory (and ~ for that matter). I've tried using an exec subshell and removing the -r from the read loop but the curl statements create a '$HOME' directory, which is not what I want to do, I want the commands to target my /home/.\+/ directory.
Since this is a strange question and you'll probably be wondering at this point (I certainly would), this is not an XY problem. I have spent a considerable time designing this piece of software and am certain that I need to store these commands in a file for my program to work and I won't consider doing otherwise unless this is proven absolutely impossible. Also, I'm not expanding $HOME myself because I want the commands to work in other users' computers.
Any ideas? Thanks in advance!
Transferring comments into an answer.
Can you use:
sh -c "$line"
Or:
eval $line
Usually eval is regarded as dangerous, but I'm not sure that sh -c is much different. Come to think of it, why not simply execute the file storing the commands?
sh "$file"
You can use sh -e "$file" to stop on an unchecked error, and add -x to see what is being executed.
Disclaimer: I'm very new to bash and for some reason I'm having a very hard time learning this one. The syntax seems very different depending on the website I visit.
I have a simple wrapper script that I want to test if a file is gzipped or not, and if so, to zcat the file to a new temporary file and open it in an editor. Here's part of the script:
if file $FILE | grep -q gzip
then
timestamp=$(date +"%D_%T")
$( zcat $FILE > tmp-$timestamp )
fi
I'm getting an error: "tmp-10/19/15_15:16:41: No such file or directory"
I tried removing the command substitution syntax or putting tmp-$timestamp in double quotes and I get the same error. If I remove the -$timestamp part, then it seems to work fine. Can someone tell me what's going on here? I'm clearing missing something very simple.
tmp-10/19/15_15:16:41 refers to a file named 15_15:16:41 in directory 19 which is a subdirectory of tmp-10. If those directories and subdirectories do not exist, you cannot write to them.
Replace:
timestamp=$(date +"%D_%T")
With:
timestamp=$(date +"%F_%T")
This gives the date without the /.
As an example of this format:
$ date +"%F_%T"
2015-10-19_12:37:05
With %F, the year comes before the month which comes before the day. This means that your files will sort properly. For most people, that is an important advantage over %D.
Revised script
Your script can be simplified to:
if file "$file" | grep -q gzip
then
zcat "$file" > "tmp-$(date +"%F_%T")"
fi
Notes:
It is best practices not to use all caps for your shell variable. The system uses all caps for its variables and you don't want to accidentally overwrite one. Use lower case or mixed case and you'll be safe.
File names, such as $file, should always be in double-quotes. Some day, someone will give you a file name with a space in it and you don't want that to cause your script to fail.
The command substitution $(...) does not belong here. It has been removed.
hey guys I'm wondering if there is a smart way to look back before a period in bash
file='foo'/bar/styles.css?ver=1.4.2
ext=$(echo ${file} | gawk -F "?" '{print$1}')
echo "${ext##*.}" # css
Seems like I should be able to do this all in my expansion somehow?
Don't think you can do it with just one bash expansion statement (unless they can be nested somehow), works fine with two though
$ start=${file%%\?*}; echo ${start##*.}
css
I am trying to automate the set up of site creation for our in-house development server.
Currently, this consists of creating a system user, mysql user, database, and apache config. I know how I can do everything in a single bash file, but I wanted to ask if there was a way to more cleanly generate the apache config.
Essentially what I want to do is generate a conf file based on a template, similar to using printf. I could certainly use printf, but I thought there might be a cleaner way, using sed or awk.
The reason I don't just want to use printf is because the apache config is about 20 lines long, and will take up most of the bash script, as well as make it harder to read.
Any help is appreciated.
Choose a way of marking parameters. One possibility is :parameter:, but any similar pair of markers that won't be confused with legitimate text for the template file(s) is good.
Write a sed script (in sed, awk, perl, ...) similar to the following:
sed -e "s/:param1:/$param1/g" \
-e "s/:param2:/$param2/g" \
-e "s/:param3:/$param3/g" \
httpd.conf.template > $HTTPDHOME/etc/httpd.conf
If you get to a point where you need sometimes to edit something and sometimes don't, you may find it easier to create the relevant sed commands in a command file and then execute that:
{
echo "s/:param1:/$param1/g"
echo "s/:param2:/$param2/g"
echo "s/:param3:/$param3/g"
if [ "$somevariable" = "somevalue" ]
then echo "s/normaldefault/somethingspecial/g"
fi
} >/tmp/sed.$$
sed -f /tmp/sed.$$ httpd.conf.template > $HTTPDHOME/etc/httpd.conf
Note that you should use a trap to ensure the temporary doesn't outlive its usefulness:
tmp=/tmp/sed.$$ # Consider using more secure alternative schemes
trap "rm -f $tmp; exit 1" 0 1 2 3 13 15 # aka EXIT HUP INT QUIT PIPE TERM
...code above...
rm -f $tmp
trap 0
This ensures that your temporary file is removed when the script exits for most plausible signals. You can preserve a non-zero exit status from previous commands and use exit $exit_status after the trap 0 command.
I'm surprised nobody mentioned here documents. This is probably not what the OP wants, but certainly a way to improve legibility of the script you started out with. Just take care to escape or parametrize away any constructs which the shell will perform substitutions on.
#!/bin/sh
# For example's sake, a weird value
# This is in single quotes, to prevent substitution
literal='$%"?*=`!!'
user=me
cat <<HERE >httpd.conf
# Not a valid httpd.conf
User=${user}
Uninterpolated=${literal}
Escaped=\$dollar
HERE
In this context I would recommend ${variable} over the equivalent $variable for clarity and to avoid any possible ambiguity.
Use sed like for example
sed s/%foo%/$foo/g template.conf > $newdir/httpd.conf
I'm thinking of using find or grep to collect the files, and maybe sed to make the change, but what to do with the output? Or would it be better to use "argdo" in vim?
Note: this question is asking for command line solutions, not IDE's. Answers and comments suggesting IDE's will be calmly, politely and serenely flagged. :-)
I am huge fan of the following
export MYLIST=`find . -type f -name *.java`
for a in $MYLIST; do
mv $a $a.orig
echo "import.stuff" >> $a
cat $a.orig >> $a
chmod 755 $a
done;
mv is evil and eventually this will get you. But I use this same construct for a lot of things and it is my utility knife of choice.
Update: This method also backs up the files which you should do using any method. In addition it does not use anything but the shell's features. You don't have to jog your memory about tools you don't use often. It is simple enough to teach a monkey (and believe me I have) to do. And you are generally wise enough to just throw it away because it took four seconds to write.
you can use sed to insert a line before the first line of the file:
sed -ie "1i import package.name.*;" YourClass.java
use a for loop to iterate through all your files and run this expression on them. but be careful if you have packages, because the import statements must be after the package declaration. you can use a more complex sed expression, if that's the case.
I'd suggest sed -i to obviate the need to worry about the output. Since you don't specify your platform, check your man pages; the semantics of sed -i vary from Linux to BSD.
I would use sed if there was a decent way to so "do this for the first line only" but I don't know of one off of the top of my head. Why not use perl instead. Something like:
find . -name '*.java' -exec perl -p -i.bak -e '
BEGIN {
print "import package.name.*;\n"
}' {} \;
should do the job. Check perlrun(1) for more details.
for i in `ls *java`
do
sed -i '.old' '1 i\
Your include statement here.
' $i
done
Should do it. -i does an in place replacement and .old saves the old file just in case something goes wrong. Replace the iterator *java as necessary (maybe 'find . | grep java' or something instead.)
You may also use the ed command to do in-file search and replace:
# delete all lines matching foobar
ed -s test.txt <<< $'g/foobar/d\nw'
see: http://bash-hackers.org/wiki/doku.php?id=howto:edit-ed
I've actually starting to do it using "argdo" in vim. First of all, set the args:
:args **/*.java
The "**" traverses all the subdir, and the "args" sets them to be the arg list (as if you started vim with all those files in as arguments to vim, eg: vim package1/One.java package1/Two.java package2/One.java)
Then fiddle with whatever commands I need to make the transform I want, eg:
:/^package.*$/s/$/\rimport package.name.*;/
The "/^package.*$/" acts as an address for the ordinary "s///" substitution that follows it; the "/$/" matches the end of the package's line; the "\r" is to get a newline.
Now I can automate this over all files, with argdo. I hit ":", then uparrow to get the above line, then insert "argdo " so it becomes:
:argdo /^package.*$/s/$/\rimport package.name.*;/
This "argdo" applies that transform to each file in the argument list.
What is really nice about this solution is that it isn't dangerous: it hasn't actually changed the files yet, but I can look at them to confirm it did what I wanted. I can undo on specific files, or I can exit if I don't like what it's done (BTW: I've mapped ^n and ^p to :n and :N so I can scoot quickly through the files). Now, I commit them with ":wa" - "write all" files.
:wa
At this point, I can still undo specific files, or finesse them as needed.
This same approach can be used for other refactorings (e.g. change a method signature and calls to it, in many files).
BTW: This is clumsy: "s/$/\rtext/"... There must be a better way to append text from vim's commandline...