CODEWITHSUNDEEP
linuxbashsed
Shivam Singh
Shivam Singh

Reputation: 41

Replace a line with a matching pattern using sed

I want to replace this line 

command: [ "--no-save", "--no-restore", "--slave", "/home/app/src/work-daily.py", "20180212"]

with 

command: [ "--no-save", "--no-restore", "--slave", "/home/app/src/work-daily.py", "20180305"]

20180305 is today's date where I am storing its value in a variable dated

My approach is 

sed 's/.*command.*/"command: \[ "--no-save", "--no-restore", "--slave", "/home/app/src/work-daily.py", "$dated"\]"/' ghj.txt

where 

dated=$(date +%Y%m%d)

its giving an error similar to this

sed: -e expression #1, char 81: unknown option to `s'

Upvotes: 4

Views: 233

Answers (3)

Rahul Verma
Rahul Verma

Reputation: 3089

I'll recommend awk for this task

You can substitute the last field in real time by calling date within awk

$ awk -F, -v OFS=, 'BEGIN{"date +%Y%m%d" | getline d} {$NF=" \""d"\"]"}1' file
command: [ "--no-save", "--no-restore", "--slave", "/home/app/src/work-daily.py", "20180305"]

"date +%Y%m%d" | getline d; : Date would get store in d

$NF=" \""d"\"]" : Replacing last field with format "date"]

Upvotes: 1

John1024
John1024

Reputation: 113994

Your command can be made to work with some change in the quoting and escaping:

$ sed 's/.*command.*/command: \[ "--no-save", "--no-restore", "--slave", "\/home\/app\/src\/work-daily.py", "'"$dated"'"\]/' ghj.txt
command: [ "--no-save", "--no-restore", "--slave", "/home/app/src/work-daily.py", "20180305"]

It looks like you only want to change the last field on lines that include the string command:. In that case, the sed command can simplify to:

$ sed -E "/command:/ s/\"[[:digit:]]+\"\]/\"$dated\"]/" ghj.txt
command: [ "--no-save", "--no-restore", "--slave", "/home/app/src/work-daily.py", "20180305"]

Alternatively, using awk:

$ awk -F\" -v d="$dated" '/command:/{$10=d} 1' OFS=\" ghj.txt
command: [ "--no-save", "--no-restore", "--slave", "/home/app/src/work-daily.py", "20180305"]

Upvotes: 1

Allan
Allan

Reputation: 12456

You can use the following sed command:

$ cat input; dated=$(date +%Y%m%d); sed "/.*command: \[ \"--no-save\", \"--no-restore\", \"--slave\", \".*work-daily.py\", \"20180212\"\]/s/201
80212/$dated/" input                                                                                                                         
command: [ "--no-save", "--no-restore", "--slave", "/home/app/src/work-daily.py", "20180212"]
command: [ "--no-save", "--no-restore", "--slave", "/home/app/src/work-daily.py", "20180305"]

where /.*command: \[ \"--no-save\", \"--no-restore\", \"--slave\", \".*work-daily.py\", \"20180212\"\]/ is used to find the proper line in the file and s/20180212/$dated/ is used to do the replacement.

Upvotes: 0

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