After changing the line to *"cmd = "blkid -o export %s | grep \'TYPE\' | cut -d\"=\" -f3" % fs"*, Now I dont see the error "SyntaxError: can't assign to literal" This is not returning exactly "*vfat*" instead of this, it is returning as "* /dev/mmcblk1p1: LABEL="efi" UUID="1084-AA42" TYPE="vfat"* "
Could you please help me as it seems to be like grep and cut commands are not working in the above line ie., on *cmd = "blkid -o export %s | grep \'TYPE\' | cut -d\"=\" -f3" % fs*? On Wed, Nov 7, 2018 at 9:41 AM Avi Gross <avigr...@verizon.net> wrote: > I may be missing something but it looks like the embedded double quotes > may be a problem in this: > > cmd = "blkid -o export %s | grep 'TYPE' | cut -d"=" -f3" % ... > > if you use single quotes as in: > > cut -d"=" > > becomes > > cut -d'=' > > or escape the double quotes with \" and so on ... > > The above seems to be seen as: > > cmd=ALPHA=BETA % ... > > where ALPHA="blkid -o export %s | grep 'TYPE' | cut -d" > and BETA=" -f3" > > Other issues may also be there. > -----Original Message----- > From: Tutor <tutor-bounces+avigross=verizon....@python.org> On Behalf Of > Alan Gauld via Tutor > Sent: Tuesday, November 6, 2018 7:37 PM > To: tutor@python.org > Cc: python-...@python.org > Subject: Re: [Tutor] SyntaxError: can't assign to literal while using > ""blkid -o export %s | grep 'TYPE' | cut -d"=" -f3" % (fs)" using > subprocess module in Python > > On 06/11/2018 18:07, srinivasan wrote: > > > bash command in python using subprocess module, I ma seeing the below > > * cmd = "blkid -o export %s | grep 'TYPE' | cut -d"=" -f3" % > > (fs)* > > In general you should try to do as little as possible using bash and > subprocess. Especially try to avoid long pipelines since you are starting a > new OS process for every element in the pipeline. That means, in your case, > you are running 4 processes to get your result - Python, blkid, grep and cut > > Python is designed to do much of what the shell command can do almost as > easily and much more efficiently (no new processes being started). > > In this case just execute the blkid bit in bash because its too difficult > to replicate simply in Python. Then use Python to search for the TYPE lines > and slice them to size. > > That will, in turn, simplify your command string and remove the issue of > multiple quotes. > > > -- > Alan G > Author of the Learn to Program web site > http://www.alan-g.me.uk/ > http://www.amazon.com/author/alan_gauld > Follow my photo-blog on Flickr at: > http://www.flickr.com/photos/alangauldphotos > > > _______________________________________________ > Tutor maillist - Tutor@python.org > To unsubscribe or change subscription options: > https://mail.python.org/mailman/listinfo/tutor > > _______________________________________________ > Tutor maillist - Tutor@python.org > To unsubscribe or change subscription options: > https://mail.python.org/mailman/listinfo/tutor > _______________________________________________ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
