How can I assign a string with quotes to a variable in bash, and use it as a pattern in awk?-CodePudding

The command that I'm using is :

objects=shubham
awk -v myvar="$objects" '($0~myvar),/REPLACE/' a.txt

the a.txt file contains

other-unwanted-content-here
target(shubham)
hello('shubham')
abc
bcd
REPLACE
other-unwanted-content-here

My desired output is:

hello('shubham')
abc
bcd
REPLACE

...but I'm getting target(shubham) as well. How can I make hello('shubham') with the quotes be the place where awk starts matching?

CodePudding user response：

Two approaches, depending on what you want.

Keep objects defined the way it is, amend your awk variable's assignment
```
objects=shubham
awk -v myvar="^hello[(]'$objects'[)]\$" '($0~myvar),/REPLACE/' <<'EOF'
```
See this running at https://ideone.com/Bto1hB

Change objects to match only the target line

objects="^hello[(]'shubham'[)]\$"
awk -v myvar="$objects" '($0~myvar),/REPLACE/' a.txt

See this running at https://ideone.com/nF8MUl

Note that in either case, ~ in awk is a regex operator; since in most regex forms (including POSIX ERE) ( and ) are syntax, we had to change your string to be a regex that matches the desired line, instead of containing exactly that line itself. (Note that in both cases, the backslash before the $ in the regex is shell syntax, not regex syntax itself, necessary only because we're in double quotes; in single quotes those backslashes would need to be left out).

CodePudding user response：

Providing the patterns are unique to the relevant lines, combining the variable in your starting line pattern (using &&) with /hello/ should fix the extra line problem:

awk -v myvar="$objects" '($0~myvar && /hello/),/REPLACE/' a.txt

output:

hello('shubham')
abc
bcd
REPLACE

Tested using mawk 1.3.4 on Raspberry Pi 400