I'm using here document of sh to run some commands. now I want to parse the output of those commands using awk. However, everytime I execute it, I get the output of the command append with something like this "% No such child process"
This is how my script looks like.
#!/bin/sh
com = "sudo -u username /path/of/file -l"
$com <<EOF | awk '{print $0}'
Commands.
.
.
.
EOF
How am I going to use heredoc and pipeline without appending that unwanted string?
Thanks
Your variable assignment is wrong in a couple of ways. First, you aren't actually assigning a variable; you're trying to run a command named com whose arguments are = and a string "sudo ...". Spaces must not be used on either side of the =:
com="sudo ..."
Second, command lines should not be stored in a variable; the shell's parser can only make that work they way you intend for very simple commands. Type the command out in full, or use a shell function.
com () {
sudo -u username /path/to/file -l
}
com <<EOF | awk '{print $0}'
...
EOF
There's no problem, check :
$ cat <<EOF | awk '{print $1}'
a b c
1 2 3
EOF
a
1
Related
Ok, so I have this command that turns off my touchscreen. It works when I execute it in a root shell.
So this works:
sudo su
/usr/bin/echo $(ls /sys/bus/hid/drivers/hid-multitouch | awk NR==1'{print $1}') > /sys/bus/hid/drivers/hid-multitouch/unbind
And then my touchscreen stops working, which is the result that I wanted.
Now I want to make a touchscreen.service file to execute this on every boot. So in the service file I include:
ExecStart=/usr/bin/echo $(ls /sys/bus/hid/drivers/hid-multitouch | awk NR==1'{print $1}') > /sys/bus/hid/drivers/hid-multitouch/unbind
However it isn't working > nor throwing any errors that I've been able to catch.
I do know from earlier fidlings with .service files that I might actually need to use /usr/bin/sh -c, so I have also tried:
ExecStart=/usr/bin/sh -c "/usr/bin/echo $(ls /sys/bus/hid/drivers/hid-multitouch | awk NR==1'{print $1}') > /sys/bus/hid/drivers/hid-multitouch/unbind"
Yet this also doesn't work.. maybe because of the awk NR==1'{print $1}'part? I have also tried replacing it with awk NR==1'\''{print $1}'\''but again it fails to work.
Does anyone have any ideas on how to get the command that is working in my root cli environment to also work as a systemd service?
To start with,
The syntax of the awk command is just wrong. The quotes are incorrectly placed. The part NR == 1 is part of the awk command to indicate the first line record in the file, i.e.
awk NR==1'{print $1}'
# ^^^^^^^ should be within quotes
awk 'NR == 1 { print $1 }'
Your sequence of echo, ls and the command substitution $(..) doesn't look right. You are effectively echo-ing the literal string /sys/bus/hid/drivers/hid-multitouch (if ls finds the file at that path) over to the pipe and awk just writes that to the /sys/bus/hid/drivers/hid-multitouch/unbind file which might not be your desired action. You just needed to do run the command on the file directly as
awk 'NR == 1 { print $1 }' /sys/bus/hid/drivers/hid-multitouch > /sys/bus/hid/drivers/hid-multitouch/unbind
Now that, that the awk command is fixed, you have two options to run the above command as part of systemd, either put your command in a script or run the command directly. For putting it in a script refer to the Unix.SE answer Where do I put scripts executed by systemd units?. As for running the command directly in ExecStart. Aside from using /bin/sh also use the path /bin/awk
So putting it together and using /bin/ over /usr/bin, you can do below. This command uses ".." over awk script and needs escape of $1
ExecStart=/bin/sh -c '/bin/awk "NR == 1 { print \$1 }" /sys/bus/hid/drivers/hid-multitouch > /sys/bus/hid/drivers/hid-multitouch/unbind'
I want to filter the output of the blkid to get the UUID.
The output of blkid looks like
CASE 1:-
$ blkid
/dev/sda2: LABEL="A" UUID="4CC9-0015"
/dev/sda3: LABEL="B" UUID="70CF-169F"
/dev/sda1: LABEL=" NTFS_partition" UUID="3830C24D30C21234"
In somecases the output of blkid looks like
CASE 2:-
$ blkid
/dev/sda1: UUID="d7ec380e-2521-4fe5-bd8e-b7c02ce41601" TYPE="ext4"
/dev/sda2: UUID="fc54f19a-8ec7-418b-8eca-fbc1af34e57f" TYPE="ext4"
/dev/sda3: UUID="6f218da5-3ba3-4647-a44d-a7be19a64e7a" TYPE="swap"
I want to filter out the UUID.
Using the combination of grep and cut it can be done as
/sbin/blkid | /bin/grep 'sda1' | /bin/grep -o -E 'UUID="[a-zA-Z|0-9|\-]*' | /bin/cut -c 7-
I have tried using awk , grep and cut as below for filtering the UUID
$ /sbin/blkid | /bin/grep 'sda1' | /usr/bin/awk '{print $2}' | /bin/sed 's/\"//g' | cut -c 7-
7ec380e-2521-4fe5-bd8e-b7c02ce41601
The above command(which uses awk) is not reliable since sometimes an extra field such as LABEL may be present in the output of the blkid program as shown in the above output.
What is the best way to create a command using awk which works reliably?
Please post if any other elegant method exits for the job using bin and core utils. I dont want to use perl or python since this has to be run on busybox.
NOTE:-I am using busybox blkid to which /dev/sda1 can not be passed as the args(the version i am using does not support it) hence the grep to filter the line.
UPDATE :- added the CASE 2: -output to show that field position can not be relied upon.
Why are you making it so complex?
Try this:
# blkid -s UUID -o value
d7ec380e-2521-4fe5-bd8e-b7c02ce41601
fc54f19a-8ec7-418b-8eca-fbc1af34e57f
6f218da5-3ba3-4647-a44d-a7be19a64e7a
Or this:
# blkid -s UUID -o value /dev/sda1
d7ec380e-2521-4fe5-bd8e-b7c02ce41601
Install proper blkid package if you don't have it:
sudo apt-get install util-linux
sudo yum install util-linux
For all the UUID's, you can do :
$ blkid | sed -n 's/.*UUID=\"\([^\"]*\)\".*/\1/p'
d7ec380e-2521-4fe5-bd8e-b7c02ce41601
fc54f19a-8ec7-418b-8eca-fbc1af34e57f
6f218da5-3ba3-4647-a44d-a7be19a64e7a
Say, only for a specific sda1:
$ blkid | sed -n '/sda1/s/.*UUID=\"\([^\"]*\)\".*/\1/p'
d7ec380e-2521-4fe5-bd8e-b7c02ce41601
The sed command tries to group the contents present within the double quotes after the UUID keyword, and replaces the entire line with the token.
Here's a short awk solution:
blkid | awk 'BEGIN{FS="[=\"]"} {print $(NF-1)}'
Output:
4CC9-0015
70CF-169F
3830C24D30C21234
Explanation:
BEGIN{FS="[=\"]"} : Use = and " as delimiters
{print $(NF-1)}: NF stands of Number of Fields; here we print the 2nd to last field
This is based on the consistent structure of blkid output: UUID in quotes is at the end of each line.
Alternatively:
blkid | awk 'BEGIN{FS="="} {print $NF}' | sed 's/"//g'
data.txt
/dev/sda2: LABEL="A" UUID="4CC9-0015"
/dev/sda3: LABEL="B" UUID="70CF-169F"
/dev/sda1: LABEL=" NTFS_partition" UUID="3830C24D30C21234"
awk and sed combination
cat data.txt | awk 'BEGIN{FS="UUID";RS="\n"} {print $2}' | sed -e 's/=//' -e 's/"//g'
Explanation:
Set the Field Separator to the string 'UUID', $2 will give the rest output
use sed then to remove the = and " as shown where -e is a switch so that you can give multiple sed commands/expression in one.
All occurrences of " are removed using the ending g option i.e. global.
The question has a "e.t.c" so I'm going to assume python is one of the options ;)
#!/usr/bin/env python3
import subprocess, re, json
# get blkid output
blkid = subprocess.check_output(["blkid"]).decode('utf-8')
devices = []
for line in [x for x in blkid.split('\n') if x]:
parameters = line.split()
for idx, parameter in enumerate(parameters):
if idx is 0:
devices.append({"DEVICE": re.sub(r':$','',parameter)})
continue
key_and_value = parameter.split('=')
devices[-1].update({
key_and_value[0]: re.sub(r'"','',key_and_value[1])
})
uuids = [{dev['DEVICE']: dev['UUID']} for dev in devices if 'UUID' in dev.keys()]
print(json.dumps(uuids, indent=4, sort_keys=True))
Although, this is probably overkill and quite a few error handling/optimization is missing from this script XD
I assume you're using busybox in an initramfs and you are waiting for your e.g. USB drive with the rootfs on it to become available.
You could use the following awk script (busybox awk compliant).
# cat get-ruuid.awk
BEGIN {
ruuid=ENVIRON["RUUID"]
}
/^\/dev\/sd[a-z]/ {
if (index($0, tolower(ruuid)) || index($0, toupper(ruuid))) {
split($1, parts, ":")
printf("%s\n", parts[1])
exit(0) # Return success and stop further scanning.
}
}
END {
exit(1) # If we reach the end, it means RUUID was not found.
}
Call it as follows from e.g. the init script; this is not the most ideal way.
# The UUID of your root partition
export RUUID="<put proper uuid value here>"
for x in 1, 2, 3, 4, 5 ; do
mdev -s
found=$(blkid | awk -f ./get-ruuid.awk)
test -z $found || break; # If no longer zero length, break the loop.
sleep 1
done
But if this is the only reason why you would want to have an initramfs, I would use the 'root=PARTUUID=... waitroot' Linux kernel command line option. Check the kernel docs and sources.
Get the proper PARTUUID (NOT UUID) of your root partition with the blkid command.
I have a csh script, my goal is to read an ini config file with perl module Config::Simple. I want to execute my perl command and assign the result to one variable.
perl -MConfig::Simple -e '$cfg = new Config::Simple("../config.ini"); $myvar = $cfg->param("myvar");'
What is the syntax ?
Receive the script's return value into a variable? I con't know the csh syntax, but in bash that is:
myvar=`perl ....`;
But if you wanted to set several variables, not sure.
For setting several variables you could have the perl script print csh syntax that the shell would evaluate.
I don't know csh but in bash it should be done like
#!/bin/sh
eval `perl -E 'say "FOO=123"; say "BAR=456"'`
echo "FOO is $FOO"
Command substitution in csh looks like this:
#!/bin/csh
set VAR=`perl -E 'say q(hello world)'`
echo ${VAR}
And, as an aside, I hope your using a descendent of csh like tcsh. The original csh implementation is a brain-dead mangled shell. This classic paper describes why.
I had a similar requirement, where I was using python instead of perl.
my python script was producing 3 output strings and the values were needed to be set in csh as variable.
Here's a solution.. hope it will help!
Inside Python:
I was using three variables : x , y and z I had only
one print statement in python which printed: x,y,z
Inside CSH:
set py_opt = `./my_python_script`
set csh_x = `echo $py_opt | sed 's/,/ /g' | awk '{print $1}'`
set csh_y = `echo $py_opt | sed 's/,/ /g' | awk '{print $2}'`
set csh_z = `echo $py_opt | sed 's/,/ /g' | awk '{print $3}'`
i want to trim an output of wipe command with sed.
i try to use this one:
wipe -vx7 /dev/sdb 2>&1 | sed -u 's/.*\ \([0-9]\+\).*/\1/g'
but it don't work for some reason.
when i use echo & sed to print the output of wipe command it works!
echo "/dev/sdb: 10%" | sed -u 's/.*\ \([0-9]\+\).*/\1/g'
what i'm doing wrong?
Thanks!
That looks like a progress indicator. They are often output directly to the tty instead of to stdout or stderr. You may be able to use the expect script called unbuffer (source) or some other method to create a pseudo tty. Be aware that there will probably be more junk such as \r, etc., that you may need to filter out.
Demonstration:
$ cat foo
#!/bin/sh
echo hello > /dev/tty
$ a=$(./foo)
hello
$ echo $a
$ a=$(unbuffer ./foo)
$ echo $a
hello
I have the following sed command. I need to execute the below command in single line
cat File | sed -n '
/NetworkName/ {
N
/\n.*ims3/ p
}' | sed -n 1p | awk -F"=" '{print $2}'
I need to execute the above command in single line. can anyone please help.
Assume that the contents of the File is
System.DomainName=shayam
System.Addresses=Fr6
System.Trusted=Yes
System.Infrastructure=No
System.NetworkName=AS
System.DomainName=ims5.com
System.DomainName=Ram
System.Addresses=Fr9
System.Trusted=Yes
System.Infrastructure=No
System.NetworkName=Peer
System.DomainName=ims7.com
System.DomainName=mani
System.Addresses=Hello
System.Trusted=Yes
System.Infrastructure=No
System.NetworkName=Peer
System.DomainName=ims3.com
And after executing the command you will get only peer as the output. Can anyone please help me out?
You can use a single nawk command. And you can lost the useless cat
nawk -F"=" '/NetworkName/{n=$2;getline;if($2~/ims3/){print n} }' file
You can use sed as well as proposed by others, but i prefer less regex and less clutter.
The above save the value of the network name to "n". Then, get the next line and check the 2nd field against "ims3". If matched, then print the value of "n".
Put that code in a separate .sh file, and run it as your single-line command.
cat File | sed -n '/NetworkName/ { N; /\n.*ims3/ p }' | sed -n 1p | awk -F"=" '{print $2}'
Assuming that you want the network name for the domain ims3, this command line works without sed:
grep -B 1 ims3 File | head -n 1 | awk -F"=" '{print $2}'
So, you want the network name where the domain name on the following line includes 'ims3', and not the one where the following line includes 'ims7' (even though the network names in the example are the same).
sed -n '/NetworkName/{N;/ims3/{s/.*NetworkName=\(.*\)\n.*/\1/p;};}' File
This avoids abuse of felines, too (not to mention reducing the number of commands executed).
Tested on MacOS X 10.6.4, but there's no reason to think it won't work elsewhere too.
However, empirical evidence shows that Solaris sed is different from MacOS sed. It can all be done in one sed command, but it needs three lines:
sed -n '/NetworkName/{N
/ims3/{s/.*NetworkName=\(.*\)\n.*/\1/p;}
}' File
Tested on Solaris 10.
You just need to put -e pretty much everywhere you'd break the command at a newline or have a semicolon. You don't need the extra call to sed or awk or cat.
sed -n -e '/NetworkName/ {' -e 'N' -e '/\n.*ims3/ s/[^\n]*=\(.*\).*/\1/P' -e '}' File