How to find if a file exists in expect script

expect

Solution

Since expect is an extension of Tcl, all Tcl commands are available to use:

if {[file exists backup.txt]} {
    send "sed -i -e 's/$oldport/$newport/' backup.txt\r"
    expect "$ "
}

Problem

I have a statement inside my expect script like this ``` send "sed -i -e 's/$oldport/$newport/' backup.txt\r" expect "$ " ``` However I wish to first check whether the file backup.txt exist and if it does, then edit it. How do I acheive this? Thanks

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