i want to get the result of the following command into a variable.
xprop -name "google-chrome-stable" | grep "window id" | awk '{print $5}' | awk '{print $1}'
the result should look something like that
OUTPUT=xprop -name "google-chrome-stable" | grep "window id" | awk '{print $5}' | awk '{print $1}'
echo $OUTPUT
I know it could be done with command substitution.
The examples in the Link command substitution are not detailed enough because they dont explain how to escape the quotation marks and apostrophes.
Could someone help me find out how to solve that?
It looks like you simply need to do this:
output=$(xprop -name "google-chrome-stable" | awk '/window id/{print $5}')
echo "$output"
There's no need to do any escaping within the $( ). I've wrapped the variable to be echoed in double quotes to prevent things like glob expansion from occurring. As a bonus, I've combined your grep and awk commands and removed the last one which wasn't doing anything useful.
I have also made your variable name lower case. Upper case variable names should be reserved for shell internals. You'll thank me for this one day when you have a variable called $PATH and suddenly everything stops working...
If you are trying to get the group leader window you can use the following instead.
output=$(xprop -notype -f WM_HINTS "32mx" ' ?m6($8)\n' -name google-chrome-stable WM_HINTS | awk '{print $2}')
echo "$output"
Arguments to -f were pulled from the xprop source itself and some man page reading about format and dformat.
The Description section of the xprop man page explains all about format and dformat.
Related
I run the command
df -gP /data1 /data2 | grep -v File | awk '{print $1}' |
awk -F/dev/ '$0=$2' | tr '\n' '
on the AIX shell (ksh) and it prints the output below:
lv_data01 lv_data02 root#testhost:/
However, I would like the output to be printed this way. Could someone help?
lv_data01 lv_data02
Using grep … | awk … | awk … is not necessary; a single awk could do the whole job. So could sed and it might even be easier. I'd be tempted to deal with the spacing by using:
x=$(df … | sed …); echo $x
The tr command, once corrected, replaces newlines with spaces, so the prompt follows without a newline before it. The ; echo suggestion adds the missing newline; the echo $x suggestion (note no double quotes) does too.
As for the sed command:
sed -n '/File/!{ s/[[:space:]].*//; s%^.*/dev/%%p; }'
Don't print anything by default
If the line doesn't match File (doing the work of grep -v):
remove the first space (blank or tab) and everything after it (doing the work of awk '{print $1}')
replace everything up to /dev/ with nothing and print (doing the work of awk -F/dev/ '{$0=$2}')
The command substitution and capture, followed by echo, deals with spaces and newlines.
So, my suggested solution is:
x=$(df -gP /data1 /data2 | sed -n '/File/!{ s/[[:space:]].*//; s%^.*/dev/%%p; }'); echo $x
You could add unset x after the echo if you are going to be using this directly in the shell and not in a shell script. If it'll be encapsulated in a shell script, you don't have to worry about it.
I'm blithely assuming the output from df -gP won't contain a path such as this, with two occurrences of /dev:
/who/knows/dev/lv_data01/dev/bin
If that's a real problem, you can fix the sed script, but I don't think it will be. It's one thing the second awk script in the question handles differently.
i'm trying to extract a specific string from a grep output
uci show minidlna
produces a large list
.
.
.
minidlna.config.enabled='1'
minidlna.config.db_dir='/mnt/sda1/usb/db'
minidlna.config.enable_tivo='1'
minidlna.config.wide_links='1'
.
.
.
so i tried to narrow down what i wanted by running
uci show minidlna | grep -oE '\bdb_dir=\S+'
this narrows the output to
db_dir='/mnt/sda1/usb/db'
what i want is to output only
/mnt/sda1/usb/db
without the quotes and without the starting "db_dir" so i can run rm /mnt/sda1/usb/db/file.db
i've used the answers found here
How to extract string following a pattern with grep, regex or perl
and that's as close as i got.
EDIT: after using Ed Morton's awk command i needed to pass the output to rm command.
i used:
| ( read DB; (rm $DB/files.db) .
read DB passes the output into the vairable DB.
(...) combines commands.
rm $DB/files.db deletes the the file files.db.
Is this what you're trying to do?
$ awk -F"'" '/db_dir/{print $2}' file
/mnt/sda1/usb/db
That will work in any awk in any shell on every UNIX box.
If that's not what you want then edit your question to clarify your requirements and post more truly representative sample input/output.
Using sed with some effort to avoid single quotes:
sed -n 's/^minidlna.config.db_dir=\s*\S\(\S*\)\S\s*$/\1/p' input
Well, so you end up having a string like db_dir='/mnt/sda1/usb/db'.
I would first remove the quotes by piping this to
.... | tr -d "'"
Now you end up with a string like db_dir=/mnt/sda1/usb/db.
Say you have this string stored in a variable named confstr, then
${confstr##*=}
gives you just /mnt/sda1/usb/db, since *= denotes everything from the start to the equal sign, and ## denotes removal.
I would do this:
Once you either extracted your line about into file.txt (or pipe it into this command), split the fields using the quote character. Use printf to generate the rm command and pass this into bash to execute.
$ awk -F"'" '{printf "rm %s.db/file.db\n", $2}' file.txt | bash
rm: /mnt/sda1/usb/db.db/file.db: No such file or directory
With your original command:
$ uci show minidlna | grep -oE '\bdb_dir=\S+' | \
awk -F"'" '{printf "rm %s.db/file.db\n", $2}' | bash
How can I rewrite the following bash command to be ShellCheck compliant?
memory=$(cat /proc/meminfo | grep 'MemTotal:' | awk {'print $2}' 2> /dev/null)
It is currently complaining about:
Useless cat. Consider 'cmd < file | ..' or 'cmd file | ..'
This { is literal.
The shellcheck complaints are
Using cat filename | grep 'pattern' instead of grep 'pattern' filename
The first brace in the awk command is on the outside of the single quote, hence literal; it should be awk '{command}'
So, a version that would satisfy shellcheck would look like
memory=$(grep 'MemTotal:' /proc/meminfo | awk '{print $2}')
I'm not sure why you redirected standard error, so I dropped it.
However, piping grep output to awk is rarely the best solution; awk can do almost anything grep can, so you could further simplify to
memory=$(awk '/MemTotal:/ { print $2 }' /proc/meminfo)
No pipes!
Just as a guess, you probably want:
memory=$(grep 'MemTotal:' /proc/meminfo | awk '{print $2}' 2> /dev/null)
However, that's a direct interpretation of the shellcheck output, so I am unsure as to what you are asking about. As it stands, you are essentially asking: "Why isn't this working?".
here is what I want to do
while ["ps a | grep '[m]ono' | awk '{print $1}'" != ""] ; do
kill ps a | grep '[m]ono' | awk '{print $1}'
done
meaning if the grep returns nothing, don't try a kill.
The thing is I've always been lost with the expression evaluation in bash, sometime I use " " around something, sometime it's eval, sometime it's ''.
Could someone explain to me how to write the condition in my loop and explain the difference between the above? I'm used to find the working one with many tries and it feels like a huge loss of time.
Best choice: Do something else.
Utilities already exist for this purpose. Example:
killall mono
pkill mono
...or, even better, something targeted to the specific executable you want to terminate:
fuser -k /path/to/something.exe
...which would kill only programs with a file handle on that specific executable, rather than all applications running with mono on the machine.
...but, to explain the bugs:
There are two things wrong here: Missing command substitutions, and missing whitespace.
Missing whitespace:
["ps a | grep '[m]ono' | awk '{print $1}'" != ""]
...is literally trying to run a command with a name starting with [ps, as in, looking in the PATH for...
/bin/[ps\ a
/usr/bin/[ps\ a
...etc. [ is a command, and needs a space after its name like any other command. Thus:
[ "ps a | grep '[m]ono' | awk '{print $1}'" != "" ]
...fixes this problem (but leaves another one).
Missing command substitutions:
[ "ps a | grep '[m]ono' | awk '{print $1}'" != "" ]
...is comparing a string that starts with "ps a" to to ""; it does not compare the output of running a command that starts with ps a. To do that, you'd instead run:
[ "$(ps a | grep '[m]ono' | awk '{print $1}')" != "" ]
The content of $(...) is replaced with the output of the command within; thus, running your pipeline and comparing its output to an empty string.
I'm trying to do some manipulation with Wordpress and I'm trying to write a script for it...
# cat /usr/local/uftwf/_wr.sh
#!/bin/sh
# $Id$
#
table_prefix=`grep ^\$table_prefix wp-config.php | awk -F\' '{print $2}'`
echo $table_prefix
#
Yet I'm getting following output
# /usr/local/uftwf/_wr.sh
ABSPATH ABSPATH wp-settings.php_KEY LOGGED_IN_KEY NONCE_KEY AUTH_SALT SECURE_AUTH_SALT LOGGED_IN_SALT NONCE_SALT wp_0zw2h5_ de_DE WPLANG WP_DEBUG s all, stop editing! Happy blogging. */
#
Running from command line, I get the correct output that I'm looking for:
# grep ^\$table_prefix wp-config.php | awk -F\' '{print $2}'
wp_0zw2h5_
#
What is going wrong in the script?
The problem is the grep command:
table_prefix=`grep ^\$table_prefix wp-config.php | awk -F\' '{print $2}'`
It either needs three backslashes - not one - or you need to use single quotes (which is much simpler):
table_prefix=$(grep '^$table_prefix' wp-config.php | awk -F"'" '{print $2}')
It's also worth using the $( ... ) notation in general.
The trouble is that the backquotes removes the backslash, so the shell variable is evaluated, and what's passed to grep is, most likely, just ^, and each line starts with a beginning of line.
This has all the appearance as though the grep is not omitting all the lines that are not matching, when you issue the echo $table_prefix without quotes it collapses all the white space into a single output line, if you issue an: echo "$table_prefix", you would see the match with all the other white-space that was output.
I'd recommend the following sed expression instead:
table_prefix=$(sed -n "s/^\$table_prefix.*'\([^']*\)'.*/\1/p" wp-config.php)
You should try
#!/bin/sh
table_prefix=$(awk -F"'" '/^\$table_prefix/{print $2}' wp-config.php)
echo $table_prefix
Does this one work for you?
awk -F\' '/^\$table_prefix/ {print $2}' wp-config.php
Update
If you are using shell scripting, there is no need to call up awk, grep:
#!/bin/sh
while read varName op varValue theRest
do
if [ "_$varName" = "_\$table_prefix" ]
then
table_prefix=${varValue//\'/} # Remove the single quotes
table_prefix=${table_prefix/;/} # Remove the semicolon
break
fi
done < wp-config.php
echo "Found: $table_prefix"