I'm looking for a way to hook in a custom bash completion function. Problem is, I want this completion function not just for a specific command, but for all commands.
Is this even possible? Having looked around for a while, I couldn't find any resources online.
To reduce the problem to the most trivial case: would it be possible to always have tab-completion for the string 'foo'?
Meaning echo f<tab> would expand into echo foo, and ls fo<tab> would expand into ls foo
For context: I'm trying to implement something similar to http://blog.plenz.com/2012-01/zsh-complete-words-from-tmux-pane.html in bash, but I'm starting to fear it's not possible.
You can do that with the -D option of the complete command:
suggest_hello()
{
COMPREPLY=( hello )
return 0
}
complete -D -F suggest_hello
Now whenever I type echo h<Tab>, I get echo hello.
$ help complete
complete: ...
...
-D apply the completions and actions as the default for commands
without any specific completion defined
...
Related
For some reason after running the main script:
sudo bash main.sh
-> execution stops at the first diff redirected to file.
However, when I comment out the function name and parentheses and call the patching.sh directly - it works.
What is wrong with my script that when calling it in a form of a function from another file - it stops, but when called directly it works?
main.sh:
set -e
source $(dirname $0)/Scripts/patching.sh
# Overwrite files
update_files
patching.sh:
#!/bin/bash
function update_files() {
declare -r SW_DIR='Source/packages/'
CMP_FILE='file1.c'
diff -u ./$SW_DIR/examples/$CMP_FILE ./Source/$CMP_FILE > file.diff
cp -v ./Source/$CMP_FILE ./$SW_DIR/examples/$CMP_FILE
}
During my debugging - I added the -x option to set. This is what I see now:
+ declare -r SW_DIR=Source/packages
+ CMP_FILE=file1.c
+ diff -u ./Source/packages/examples/file1.c ./Source/file1.c
And that's the last line. If I omit the redirection operator - the diff is simply shown in the console and that's it. It does not proceed further, with no error message.
See What does set -e mean in a bash script? and BashFAQ/105 (Why doesn't set -e (or set -o errexit, or trap ERR) do what I expected?). Execution stops after the diff when set -e is in effect because diff exits with non-zero status when the files that it is comparing are different. This kind of behaviour is one of the downsides of using set -e. Follow the links for more, and useful, information.
When I'm looking at bash script code, I sometimes see | and sometimes see ||, but I don't know which is preferable.
I'm trying to do something like ..
set -e;
ret=0 && { which ansible || ret=$?; }
if [[ ${ret} -ne 0 ]]; then
# install ansible here
fi
Please advise which OR operator is preferred in this scenario.
| isn't an OR operator at all. You could use ||, though:
which ansible || {
true # put your code to install ansible here
}
This is equivalent to an if:
if ! which ansible; then
true # put your code to install ansible here
fi
By the way -- consider making a habit of using type (a shell builtin) rather than which (an external command). type is both faster and has a better understanding of shell behavior: If you have an ansible command that's provided by, say, a shell function invoking the real command, which won't know that it's there, but type will correctly detect it as available.
There is a big difference between using a single pipe (pipe output from one command to be used as input for the next command) and a process control OR (double pipe).
cat /etc/issue | less
This runs the cat command on the /etc/issue file, and instead of immediately sending the output to stdout it is piped to be the input for the less command. Yes, this isn't a great example, since you could instead simply do less /etc/issue - but at least you can see how it works
touch /etc/testing || echo Did not work
For this one, the touch command is run, or attempted to run. If it has a non-zero exit status, then the double pipe OR kicks in, and tries to execute the echo command. If the touch command worked, then whatever the other choice is (our echo command in this case) is never attempted...
I am after a bash script which I can use to trigger a delta import of XML files via CRON. After a bit of digging and modification I have this:
#!/bin/bash
# Bash to initiate Solr Delta Import Handler
# Setup Variables
urlCmd='http://localhost:8080/solr/dataimport?command=delta-import&clean=false'
statusCmd='http://localhost:8080/solr/dataimport?command=status'
outputDir=.
# Operations
wget -O $outputDir/check_status_update_index.txt ${statusCmd}
2>/dev/null
status=`fgrep idle $outputDir/check_status_update_index.txt`
if [[ ${status} == *idle* ]]
then
wget -O $outputDir/status_update_index.txt ${urlCmd}
2>/dev/null
fi
Can I get any feedback on this? Is there a better way of doing it? Any optimisations or improvements would be most welcome.
This certainly looks usable. Just to confirm, you intend to run this ever X minutes from your crontab? That seems reasonsable.
The only major quibble (IMHO) is discarding STDERR information with 2>/dev/null. Of course it depends on what are your expectations for this system. If this is for a paying customer or employer, do you want to have to explain to the boss, "gosh, I didn't know I was getting error message 'Cant connect to host X' for the last 3 months because we redirect STDERR to /dev/null"! If this is for your own project, and your monitoring the work via other channels, then not so terrible, but why not capture STDERR to file, and if check that there are no errors. as a general idea ....
myStdErrLog=/tmp/myProject/myProg.stderr.$(/bin/date +%Y%m%d.%H%M)
wget -O $outputDir/check_status_update_index.txt ${statusCmd} 2> ${myStdErrLog}
if [[ ! -s ${myStdErrLog} ]] ; then
mail -s "error on myProg" me#myself.org < ${myStdErrLog}
fi
rm ${myStdErrLog}
Depending on what curl includes in its STDERR output, you may need filter what is in the StdErrLog to see if there are "real" error messages that you need to have sent to you.
A medium quibble is your use backticks for command substitution, if you're using dbl-sqr-brackets for evaluations, then why not embrace complete ksh93/bash semantics. The only reason to use backticks is if you think you need to be ultra-backwards compatible and that you'll be running this script under the bourne shell (or possibly one of the stripped down shells like dash).Backticks have been deprecated in ksh since at least 1993. Try
status=$(fgrep idle $outputDir/check_status_update_index.txt)
The $( ... ) form of command substitution makes it very easy to nest multiple cmd-subtitutions, i.e. echo $(echo one $(echo two ) ). (Bad example, as the need to nest cmd-sub is pretty rare, I can't think of a better example right now).
Depending on your situation, but in a large production environement, where new software is installed to version numbered directories, you might want to construct your paths from variables, i.e.
hostName=localhost
portNum=8080
SOLRPATH=/solr
SOLRCMD='delta-import&clean=false"
urlCmd='http://${hostName}:${portNum}${SOLRPATH}/dataimport?command=${SOLRCMD}"
The final, minor quibble ;-). Are you sure ${status} == *idle* does what you want?
Try using something like
case "${status}" in
*idle* ) .... ;;
* ) echo "unknown status = ${status} or similar" 1>&2 ;;
esac
Yes, your if ... fi certainly works, but if you want to start doing more refined processing of infomation that you put in your ${status} variable, then case ... esac is the way to go.
EDIT
I agree with #alinsoar that 2>/dev/null on a line by itself will be a no-op. I assumed that it was a formatting issue, but looking in edit mode at your code I see that it appears to be on its own line. If you really want to discard STDERR messages, then you need cmd ... 2>/dev/null all on one line OR as alinsoar advocates, the shell will accept redirections at the front of the line, but again, all on one line ;-!.
IHTH
In bash I am able to write a script that contains something like this:
{ time {
#series of commands
echo "something"
echo "another command"
echo "blah blah blah"
} } 2> $LOGFILE
In ZSH the equivalent code does not work and I can not figure out how to make it work for me. This code works but I don't exactly know how to get it to wrap multiple commands.
{ time echo "something" } 2>&1
I know I can create a new script and put the commands in there then time the execution properly, but is there a way to do it either using functions or a similar method to the bash above?
Try the following instead:
{ time ( echo hello ; sleep 10s; echo hola ; ) } 2>&1
If you want to profile your code you have a few alternatives:
Time subshell execution like:
time ( commands ... )
Use REPORTTIME to check for slow commands:
export REPORTTIME=3 # display commands with execution time >= 3 seconds
setop xtrace as explained here
The zprof module
Try replace { with ( ?
I think this should help
You can also use the times POSIX shell builtin in conjunction with functions.
It will report the user and system time used by the shell and its children. See
http://pubs.opengroup.org/onlinepubs/009695399/utilities/times.html
Example:
somefunc() {
code you want to time here
times
}
The reason for using a shell function is that it creates a new shell context, at the start of which times is all zeros (try it). Otherwise the result contains the contribution of the current shell as well. If that is what you want, forget about the function and put times last in your script.
I'm trying to write a small command launcher application, and would like to use bash's tab completions in my own completion system. I've been able to get a list of completions for general commands using compgen -abck.
However, I would also like to get completions for specific commands: for instance, the input git p should display completion for git's commands.
Is there any way I can use compgen to do this? If not, are there any other ways I can get a list of completions programmatically?
[EDIT: To clarify, I'm not trying to provide completion to bash - my app is a GUI command launcher. I'd simply like to use bash's existing completions in my own app.]
I don't really know how it works, but the awesome window manager uses the following Lua code for getting access to bash completion's result:
https://github.com/awesomeWM/awesome/blob/master/lib/awful/completion.lua#L119
Via complete -p we find complete -o bashdefault -o default -o nospace -F _git git. We remember "_git" for later.
The length of "git l" is 5, so we set COMP_COUNT=6. We are completing the first argument to "git", so COMP_CWORD=1.
All together we use the following script:
__print_completions() {
printf '%s\n' "${COMPREPLY[#]}"
}
# load bash-completion functions
source /etc/bash_completion
# load git's completion function
_completion_loader git
COMP_WORDS=(git l)
COMP_LINE='git l'
COMP_POINT=6
COMP_CWORD=1
_git
__print_completions
Output: "log"
Check in the /etc/bash_completion.d/ directory. This is where the different command completion scripts stay.
Quite an old question, but in the mean time I've implemented a script that handles this to reuse completions with ZSH
Here a simple but working example in bash :
function foo_completion()
{
local currentWord=${COMP_WORDS[COMP_CWORD]}
local completionList=""
case "${COMP_CWORD}" in
"1")
completionList="command1 command2 command3";
;;
"2")
completionList="param1 param2 param3";
;;
esac
COMPREPLY=( $( compgen -W "${completionList}" -- ${currentWord} ) )
}
complete -F foo_completion foo
With this kind of code, you will get commandN completed when you type "foo c" + tab and paramN completed when you type "foo command1 p" + tab
You can compute the completion list from the command help.
my2c