Ubuntu – Replace a pattern containing an apostrophe within a file

awkcommand linesedtext processing

I have a text file which contains this line:

set stime = '0 0'

I need to change that to:

set stime = '0 4'

I tried these commands:

sed -i 's/original/new/g' file.txt

and

awk '{gsub(/pattern/,"replacement")}' file

but they don't work. I guess it is because of the apostrophe in the pattern. How can I do this correctly?

Best Answer

In order to escape single quote ', you should use double quotes: ".

In order to update in-place you should use sed -i

The following code should update in-place, and escape the single quote:

sed -i "s/set stime = '0 0'/set stime = '0 4'/g" input_file_name

Related Solutions

Ubuntu – Split text file into several ones when pattern appears, with command line in linux

You could use awk with some redirection:

awk -F/ '/^PAT/{close(file);file = $NF; next} /./{print >> file}' foo

The result:

$ head page0*
==> page01 <==
ABC
DEF    

==> page02 <==
GHI
JKL    

==> page03 <==
MNO
PQR

Essentially, for each line beginning with PAT, I'm saving the last field (via a field separator of /) the variable file, and then printing every non-empty line (/./ matches lines with at least one character) to the name contained in file.

Note that it's important to close the previous file at each loop to prevent a "makes too many open files" error when there's "a lot" of file created.

Ubuntu – Replace spaces in a matched substring with underscores

Through python,

$ echo 'href="./Dynamic Directory name - Junk_files/irrelevant stuff after match"' |
> python -c "import re;
> import sys;
> print re.sub(r'(?<=\./).*?(?=/)', lambda m: m.group().replace(' ', '_'), sys.stdin.read())
> "
href="./Dynamic_Directory_name_-_Junk_files/irrelevant stuff after match"

Through perl,

$ echo 'href="./Dynamic Directory name - Junk_files/irrelevant stuff' | perl -pe '
> s/\s(?=(?:(?!\.\/).)*?\/)/_/g
> '
href="./Dynamic_Directory_name_-_Junk_files/irrelevant stuff

Best Answer

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Ubuntu – Split text file into several ones when pattern appears, with command line in linux

Ubuntu – Replace spaces in a matched substring with underscores

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