要替换第三行:

$ cat junk.txt
sic transit
gloria mundi
temeo danoas
et dona ferentes

执行此操作:

> latin = readLines("junk.txt",-1)
> latin[3]="per ardua ad astra"
> writeLines(latin,"junkout.txt")

并获得:

$ cat junkout.txt 
sic transit
gloria mundi
per ardua ad astra
et dona ferentes

如果需要，可以writeLines(latin,"junk.txt")并覆盖输入文件.

You can writeLines(latin,"junk.txt") and overwrite the input file if you want.