在script中移除變數中的換行符號

寫bash script時候, 用grep或awk取出來的值, 裡面還包含了一些non-printable的字; 作字串比對時, 就會一直出錯. 這時可以用 tr 這個指令移除看不到的字(如換行符號):

# echo $VAR_WITH_NON_PRINT | tr -d '/r/n'
這樣就可以移除換行符號
還有更多種選擇:
       \NNN   character with octal value NNN (1 to 3 octal digits)

       \\     backslash

       \a     audible BEL

       \b     backspace

       \f     form feed

       \n     new line

       \r     return

       \t     horizontal tab

       \v     vertical tab

       CHAR1-CHAR2
              all characters from CHAR1 to CHAR2 in ascending order

       [CHAR*]
              in SET2, copies of CHAR until length of SET1

       [CHAR*REPEAT]
              REPEAT copies of CHAR, REPEAT octal if starting with 0

       [:alnum:]
              all letters and digits

       [:alpha:]
              all letters

       [:blank:]
              all horizontal whitespace

       [:cntrl:]
              all control characters

       [:digit:]
              all digits

       [:graph:]
              all printable characters, not including space

       [:lower:]
              all lower case letters

       [:print:]
              all printable characters, including space

       [:punct:]
              all punctuation characters

       [:space:]
              all horizontal or vertical whitespace

       [:upper:]
              all upper case letters

       [:xdigit:]
              all hexadecimal digits

       [=CHAR=]
              all characters which are equivalent to CHAR