I'm trying to change the exstension of a file passing the arguments by console
system = "rename" , "'s/\#{ARGV[0]}$/\#{ARGV[1]}'", "*#{ARGV[1]}"
The code is correct because it works on console but when I put it in a script I have trouble with
s/\#
because it appears in pink and the console does not get it.
you don't want to send literal single quotes, so remove them.
you want to remove the backslashes so you let Ruby evaluate those expressions.
you're missing the trailing slash.
what's that equal sign doing?
did you want ARGV[0] in the last argument to rename, instead of ARGV[1]?
you want to use * wildcard, which requires a shell to expand into a list of files, which means you can't use the list form of system
Try
system "/usr/bin/rename -n 's/#{ARGV[0]}$/#{ARGV[1]}/' *#{ARGV[0]}"
Remove the -n option if it looks like you're going to rename the way you want.
And, of course, you don't need to call out to the shell for this:
Dir.glob("*#{ARGV[0]}").each {|fname|
newname = fname.sub(/#{ARGV[0]}$/, ARGV[1])
File.rename(fname, newname)
}
Related
A config file that the last line contains data that I want to assign everything to the RIGHT of the = sign into a variable that I can display and call later in the script.
Example: /path/to/magic.conf:
foo
bar
ThisOption=foo.bar.address:location.555
What would be the best method in a bash shell script to read the last line of the file and assign everything to the right of the equal sign? In this case, foo.bar.address:location.555.
The last line always has what I want to target and there will only ever be a single = sign in the file that happens to be the last line.
Google and searching here yielded many close but non-relative results with using sed/awk but I couldn't come up with exactly what I'm looking for.
Use sed:
variable=$(sed -n 's/^ThisOption=//p' /path/to/magic.conf)
echo "The option is: $variable")
This works by finding and removing the ThisOption= marker at the start of the line, and printing the result.
IMPORTANT: This method absolutely requires that the file be trusted 100%. As mentioned in the comments, anytime you "eval" code without any sanitization there are grave risks (a la "rm -rf /" magnitude - don't run that...)
Pure, simple bash. (well...using the tail utility :-) )
The advantage of this method, is that it only requires you to know that it will be the last line of the file, it does not require you to know any information about that line (such as what the variable to the left of the = sign will be - information that you'd need in order to use the sed option)
assignment_line=$(tail -n 1 /path/to/magic.conf)
eval ${assignment_line}
var_name=${assignment_line%%=*}
var_to_give_that_value=${!var_name}
Of course, if the var that you want to have the value is the one that is listed on the left side of the "=" in the file then you can skip the last assignment and just use "${!var_name}" wherever you need it.
I'm using jamplus to build a vendor's cross-platform project. On osx, the C tool's command line (fed via clang to ld) is too long.
Response files are the classic answer to command lines that are too long: jamplus states in the manual that one can generate them on the fly.
The example in the manual looks like this:
actions response C++
{
$(C++) ##(-filelist #($(2)))
}
Almost there! If I specifically blow out the C.Link command, like this:
actions response C.Link
{
"$(C.LINK)" $(LINKFLAGS) -o $(<[1]:C) -Wl,-filelist,#($(2:TC)) $(NEEDLIBS:TC) $(LINKLIBS:TC))
}
in my jamfile, I get the command line I need that passes through to the linker, but the response file isn't newline terminated, so link fails (osx ld requires newline-separated entries).
Is there a way to expand a jamplus list joined with newlines? I've tried using the join expansion $(LIST:TCJ=\n) without luck. $(LIST:TCJ=#(\n)) doesn't work either. If I can do this, the generated file would hopefully be correct.
If not, what jamplus code can I use to override the link command for clang, and generate the contents on the fly from a list? I'm looking for the least invasive way of handling this - ideally, modifying/overriding the tool directly, instead of adding new indirect targets wherever a link is required - since it's our vendor's codebase, as little edit as possible is desired.
The syntax you are looking for is:
newLine = "
" ;
actions response C.Link
{
"$(C.LINK)" $(LINKFLAGS) -o $(<[1]:C) -Wl,-filelist,#($(2:TCJ=$(newLine))) $(NEEDLIBS:TC) $(LINKLIBS:TC))
}
To be clear (I'm not sure how StackOverflow will format the above), the newLine variable should be defined by typing:
newLine = "" ;
And then placing the carat between the two quotes and hitting enter. You can use this same technique for certain other characters, i.e.
tab = " " ;
Again, start with newLine = "" and then place carat between the quotes and hit tab. In the above it is actually 4 spaces which is wrong, but hopefully you get the idea. Another useful one to have is:
dollar = "$" ;
The last one is useful as $ is used to specify variables typically, so having a dollar variable is useful when you actually want to specify a dollar literal. For what it is worth, the Jambase I am using (the one that ships with the JamPlus I am using), has this:
SPACE = " " ;
TAB = " " ;
NEWLINE = "
" ;
Around line 28...
I gave up on trying to use escaped newlines and other language-specific characters within string joins. Maybe there's an awesome way to do that, that was too thorny to discover.
Use a multi-step shell command with multiple temp files.
For jamplus (and maybe other jam variants), the section of the actions response {} between the curly braces becomes an inline shell script. And the response file syntax #(<value>) returns a filename that can be assigned within the shell script, with the contents set to <value>.
Thus, code like:
actions response C.Link
{
_RESP1=#($(2:TCJ=#)#$(NEEDLIBS:TCJ=#)#$(LINKLIBS:TCJ=#))
_RESP2=#()
perl -pe "s/[#]/\n/g" < $_RESP1 > $_RESP2
"$(C.LINK)" $(LINKFLAGS) -o $(<[1]:C) -Wl,-filelist,$_RESP2
}
creates a pair of temp files, assigned to shell variable names _RESP1 and _RESP2. File at path _RESP1 is assigned the contents of the expanded sequence joined with a # character. Search and replace is done with a perl one liner into _RESP2. And link proceeds as planned, and jamplus cleans up the intermediate files.
I wasn't able to do this with characters like :;\n, but # worked as long as it had no adjacent whitespace. Not completely satisfied, but moving on.
I am working on a shell script to retrieve variable content from a JSON file via JQ. The JSON file is in string format (no matter whether this is a real string or a number) and to retrieve the variable in my bash script I did something like this
my_domain=$(cat /vagrant/data_bags/config.json | jq ."app"[0]."domain")
The above code once echoed results in "mydomain" with a beginning and a trailing quote sign. I though this was a normal behaviour of the echo command. However, while concatenating my variable with another shell command the system raise an error. For instance, the following command
cp /vagrant/public_html/index.php "/var/www/"+$my_domain+"/index.php"
fails with the following error
cp: cannot create regular file `/var/www/+"mydomain"+/index.php': No such file or directory
At this stage, I wasn't able to identify whether it's me doing the wrong concatenation with the plus sign or the variable is effectively including the quotes that in any case will end up generating an error.
I have tried to replace the quotes in my variable, but I ended up getting the system raising a "Command not found" error.
Can somebody suggest what am I doing wrong?
+ is not used for string concatenation in bash (or perl, or php). Just:
cp /vagrant/public_html/index.php "/var/www/$my_domain/index.php"
Embedding a variable inside a double-quoted text string is known as interpolation, and is one of the reasons why we need the $ prefix, to indicate that this is a variable. Interpolation is specifically not done inside single quoted strings.
Braces ${my_domain} are not required because the / directory separators are not valid characters in a variable name, so there is no ambiguity.
For example:
var='thing'
echo "Give me your ${var}s" # Correct, appends an 's' after 'thing'
echo "Give me your $vars" # incorrect, looks for a variable called vars.
If a variable (like 'vars') does not exist then (by default) it will not complain, it will just give an empty string. Braces (graph brackets) are required more in c-shell (csh or tcsh) because of additional syntax for modifying variables, which involves special trailing characters.
You don't need to use + to concatenate string in bash, change your command to
cp /vagrant/public_html/index.php "/var/www/"${my_domain}"/index.php"
My problem was not related only to the wrong concatenation, but also to the JQ library that after parsing the value from the JSon file was returning text between quotes.
In order to avoid JQ doing this, just add the -rawoutput parameter when calling JQ.
I'm trying to make a script that will go into a directory and run my own application with each file matching a regular expression, specifically Test[0-9]*.txt.
My input filenames look like this TestXX.txt. Now, I could just use cut and chop off the Test and .txt, but how would I do this if XX wasn't predefined to be two digits? What would I do if I had Test1.txt, ..., Test10.txt? In other words, How would I get the [0-9]* part?
Just so you know, I want to be able to make a OutputXX.txt :)
EDIT:
I have files with filename Test[0-9]*.txt and I want to manipulate the string into Output[0-9]*.txt
Would something like this help?
#!/bin/bash
for f in Test*.txt ;
do
process < $f > ${f/Test/Output}
done
Bash Shell Parameter Expansion
A good tutorial on regexes in bash is here. Summarizing, you need something like:
if [[$filenamein =~ "^Test([0-9]*).txt$"]]; then
filenameout = "Output${BASH_REMATCH[1]}.txt"
and so on. The key is that, when you perform the =~" regex-match, the "sub-matches" to parentheses-enclosed groups in the RE are set in the entries of arrayBASH_REMATCH(the[0]entry is the whole match,1` the first parentheses-enclosed group, etc).
You need to use rounded brackets around the part you want to keep.
i.e. "Test([0-9]*).txt"
The syntax for replacing these bracketed groups varies between programs, but you'll probably find you can use \1 , something like this:
s/Test(0-9*).txt/Output\1.txt/
If you're using a unix shell, then 'sed' might be your best bet for performing the transformation.
http://www.grymoire.com/Unix/Sed.html#uh-4
Hope that helps
for file in Test[0-9]*.txt;
do
num=${file//[^0-9]/}
process $file > "Output${num}.txt"
done
How do I write a shell script (bash on HPUX) that receives a string as an argument containing an asterisk?
e.g. myscript my_db_name "SELECT * FROM table;"
The asterisk gets expanded to all the file names in the current directory, also if I assign a variable like this.
DB_QUERY="$2"
echo $DB_QUERY
The asterisk "*" is not the only character you have to watch out for, there's lots of other shell meta-charaters that can cause problems, like < > $ | ; &
The simple answer is always to put your arguments in quotes (that's the double-quote, " ) when you don't know what they might contain.
For your example, you should write:
DB_QUERY="$2"
echo "$DB_QUERY"
It starts getting awkward when you want your argument to be used as multiple parameters or you start using eval, but you can ask about that separately.
You always need to put double quotes around a variable reference if you want to prevent it from triggering filename expansion. So, in your example, use:
DB_QUERY="$2"
echo "$DB_QUERY"
In the first example, use single quotes:
myscript my_db_name 'SELECT * FROM table;'
In the second example, use double quotes:
echo "$DB_QUERY"