如何通过$ @将包含空格的sed命令传递给Bash函数

Question

I would need to replace a string having spaces with another string in a file in a bash script where all calls should be done through a function that writes the command to a log file and then runs the command. The logrun function uses special character $@ for reading in the command. I'm trying to use sed for replacing but I can't find a way to escape spaces when the sed command having spaces in expression parameter goes through $@ .

I have simplified the problem to test scripts where I use sed for replacing ac with abc .

test1.sh works great:

#!/bin/bash

TESTFILE=/tmp/test.txt
echo "a c" > $TESTFILE
sed -i -e 's/a c/a b c/' $TESTFILE

test2.sh fails:

#!/bin/bash

function logrun() {
    CMD=$@
    $CMD
}

TESTFILE=/tmp/test.txt
echo "a c" > $TESTFILE
logrun sed -i -e 's/a c/a b c/' $TESTFILE

Result:

sed: -e expression #1, char 3: unterminated `s' command

The reason for error is the space(s) in the -e expression. I haven't found a way to call sed through that function. I have tried to use double quotes instead of single quotes and to escape spaces with a backslash etc. I am really curious to find out what's the correct way to do it.

Answer 1

logrun() {
    CMD=("$@")
    "${CMD[@]}"
}

Writing $@ without quotes combines all of the arguments into one space-separated string. "$@" with quotes keeps each argument separate and preserves whitespace.

Writing just CMD="$@" would create a simple string variable. CMD=("$@") creates an array.

Then, to expand the array, use the same syntax as you did with PARAMS : "${CMD[@]}" . The quotes and the two sets of braces are all necessary. Don't leave any of them out.

By the way, if you don't need the CMD variable, it could be a lot less verbose:

logrun() {
    "$@"
}