I want to use the os.system command in order to get some information during a python script execution, but I get a syntax error, I'm literally using the same command on the terminal and the syntax it's correct.
the command is:
os.system(['df -h / | grep -E "\/$" | awk '{printf( $4)}''])
but the syntax error appears on the {
thanks in advance.
You're inconsistent with your single vs double quotes. Stack overflow's syntax coloring should make this clear.
You can fix your syntax error by escaping quotes as done by l'L'l, though I prefer wrapping the string in triple quotes. This avoids the need for escaped quotes (e.g. \').
os.system(["""df -h / | grep -E "\/$" | awk '{printf( $4)}'"""])
Then you'll just have a TypeError because the function doesn't expect a list. Fix it like this:
os.system("""df -h / | grep -E "\/$" | awk '{printf( $4)}'""")
Related
I'm trying to inline a jq construct that itself requires pipes. I suspect I'm running into issues because bash is treating them as bash-level pipes, rather than part of the jq.
Testing at jqplay.org, this .[1] | [.timeEnded, .lifecycleState] | flatten gets me the result I need.
Trying to embed that in bash, I am trying to do something like:
status=$(curl -X GET <URL> | jq -r -c '.[1] | [.timeEnded, .lifecycleState] | flatten' | awk -F, '{print $2}' | sed 's/"//g')
With no escaping the pipes within the jq, I get
[.timeEnded,: command not found
I tried to escape those pipes as jq -r -c '.[1] \| [.timeEnded, .lifecycleState] \| flatten' but that gets me a jq syntax error:
jq: error: syntax error, unexpected INVALID_CHARACTER, expecting $end (Unix shell quoting issues?) at <top-level>, line 1:
.[1] \| [.timeEnded, .lifecycleState] \| flatten
jq: 1 compile error
Wrapping the entire jq command in double quotes (as well as the escape chars) gave me the same syntax error. I'm sure there's probably an easy answer here, but jq is new to me.
Any help would be appreciated.
I clearly suspect that you have an unbreakable space in this part:
jq -r -c '.[1] | [...
So, edit the line manually, and replace all spaces with real spaces (taking care to not type unbreakable spaces again with AltGr+space)
Embedding jq in bash - what needs to be escaped?
Using bash and bash-like shells, jq programs can often be specified quite simply on the command line using single-quoted strings, e.g.
$ jq -n '"abc"'
"abc"
However, using this technique, single quotes are a headache since bash
does not allow single quotes within ordinary single-quoted strings. The workaround is quite horrible:
$ jq -n '"a'"'"'b"'
"a'b"
So if the jq program does have embedded single-quotes, then
it's probably time to use the -f option, but if that is not
an option, then using the form $'STRING' should be considered.
In this case, though, there are two characters that can occur in jq programs and
that will require attention: single-quotes and backslashes
For example:
$ jq -n $'"a\\tb" | "\'\\(.)\'"'
"'a\tb'"
If I'm not mistaken, the required escaping can be done using:
sed -e $'s/\'/\\\'/g' -e $'s/\\\\/\\\\\\\\/g'
I have used the below command, and It will get some substring in attribute value.
skipped=$(echo "$value" | jq -f '.[].output | scan("totalSkipped+: [[:digit:]]+")' | sed 's/"//g' )
I ran this script in shell through Jenkins job. and observed below error message:
/tmp/jenkins7615126817764256878.sh: command substitution: line 30: syntax error near unexpected token `"totalSkipped+: [[:digit:]]+"'
/tmp/jenkins7615126817764256878.sh: command substitution: line 30: `echo "$value" | jq .[].output | scan("totalSkipped+: [[:digit:]]+") | sed 's/"//g' )'
I have the entire json file which is stored in $value variable and echo "$value" returned the content of json file but not sure why its not working in jenkins.
I used the same command in jq online tool but It works as expected.
https://jqplay.org/s/7lBj_kDoB3
I'm using jq-1.6 version.
Can someone help me to resolve this?
skipped=$(jq -r '.[].output | scan("totalSkipped: [[:digit:]]+")' <<<"$value")
The pipeline is jq syntax, so it needs to be inside single quotes so the shell doesn't try to find a separate shell command named scan.
No reason for sed here -- using the -r argument to jq makes it emit raw strings as output, so they don't have syntactic quotes.
I am running a script and this is part of it:
cat ../my_file.txt | sed -e $'s/\t#.*$/found_pattern/g'
This is quite working. So far, so good. Now I want to use this part as a variable $'s/\t#.*$/found_pattern/g'
When I am trying to run the following it wont work:
THISVAR="$'s/\t#.*$/found_pattern/g'"
cat ../my_file.txt | sed -e ${THISVAR}
I think the dollar sign won't get interpreted.
Can you guys help me out?
Thanks and have a great day.
When you put $ in quotes it became part of the variable's value instead of being used as a meta-character to interpret escape sequences. Try this:
THISVAR=$'s/\t#.*$/found_pattern/g'
cat ../my_file.txt | sed -e "$THISVAR"
Double-quote THISVAR to interpret the variable but prevent shell from tokenizing its value before passing to sed.
Also, you don't need the cat - just pass the file name to sed directly.
sed -e "$THISVAR" ../my_file.txt
I am trying to write a script that should take values from a xml file.
Here is the xml file :-
`<manifestFile>
<productInformation>
<publicationInfo>
<pubID pcsi-selector="P.S.">PACODE</pubID>
<pubNumber/>
</publicationInfo>
</productInformation>
</manifestFile>`
and i my code is
:-
#!/bin/sh
Manifest=""
Manifest= `/bin/grep 'pcsi-selector="' /LDCManifest.xml | cut -f 2 -d '"'`
echo $Manifest
I expect my result to be P.S. , but it keeps throwing error as :-
./abc.sh: P.S.: not found
I am new to shell and i am not able to figure out whats the error here ?
You can't have a space after the =.
When you run this command:
Manifest= `/bin/grep 'pcsi-selector="' /LDCManifest.xml | cut -f 2 -d '"'`
It's the same as this:
Manifest='' `/bin/grep 'pcsi-selector="' /LDCManifest.xml | cut -f 2 -d '"'`
That tells the shell to
Run the grep command.
Take its output
Run that output as a command, with the environment variable Manifest set to the empty string for the duration of the command.
Get rid of the space after the = and you'll get the result you want.
However, you should also avoid using backticks for command substitution, because they interfere with quoting. Use $(...) instead:
Manifest=$(grep 'pcsi-selector="' /LDCManifest.xml | cut -f2 -d'"')
Also, using text/regex-based tools like grep and cut to manipulate XML is clunky and error-prone. You'd be better off installing something like XMLStarlet:
Manifest=$(xmlstarlet sel -t \
-v '/manifestFile/productInformation/publicationInfo/pubID/#pcsiselector' -n \
/LDCManifest.xml)
Or simpler:
grep -oP 'pcsi-selector="\K[^"]+' /LDCManifest.xml
would print
P.S.
assign
Manifest=$(grep -oP 'pcsi-selector="\K[^"]+' /LDCManifest.xml)
I am trying to run this command on MacOSX terminal , which was initially intended to run on Linux
sed '1 i VISPATH=/mnt/local/gdrive/public/3DVis' init.txt >> ~/.bash_profile
but it gives me the error:
command i expects \ followed by text.
is there any way I could modify the above command to work on MacOSX terminal
Shelter is right but there's another way to do it. You can use the bash $'...' quoting to interpret the escapes before passing the string to sed.
So:
sed -iold '1i\'$'\n''text to prepend'$'\n' file.txt
^^^^^^^^ ^
/ |\|||/ \ |__ No need to reopen
| | \|/ | string to sed
Tells sed to | | | |
escape the next _/ | | +-----------------------------+
char | +-------------+ |
| | |
Close string The special bash Reopen string to
to sed newline char to send to sed
send to sed
This answer on unix.stackexchange.com led me to this solution.
Had the same problem and solved it with brew:
brew install gnu-sed
gsed YOUR_USUAL_SED_COMMAND
If you want to use the sed command, then you can set an alias:
alias sed=gsed
The OSX seds are based on older versions, you need to be much more literal in your directions to sed, AND you're lucky, in this case, sed is telling you exactly what to do. Untested as I don't have OSX, but try
sed '1 i\
VISPATH=/mnt/local/gdrive/public/3DVis
' init.txt >> ~/.bash_profile
Input via the i cmd is terminated by a blank line. Other sed instructions can follow after that. Note, NO chars after the \ char!
Also, #StephenNiedzielski is right. Use the single quote chars to wrap your sed statements. (if you need variable expansion inside your sed and can escape other uses of $, then you can also use dbl-quotes, but it's not recommended as a normal practices.
edit
As I understand now that you're doing this from the command-line, and not in a script or other editor, I have tested the above, and.... all I can say is that famous line from tech support ... "It works for me". If you're getting an error message
sed: -e expression #1, char 8: extra characters after command
then you almost certainly have added some character after the \. I just tested that, and I got the above error message. (I'm using a linux version of sed, so the error messages are exactly the same). You should edit your question to include an exact cut-paste of your command line and the new error message. Using curly-single-quotes will not work.
IHTH
Here's how I worked it out on OS X. In my case, I needed to prepend text to a file. Apparently, modern sed works like this:
sed -i '1i text to prepend' file.txt
But on OS X I had to do the following:
sed -i '' '1i\
text to prepend
' file.txt
It looks like you copied rich text. The single quotes should be straight not curly:
sed '1 i VISPATH=/mnt/local/gdrive/public/3DVis'