hi,

am not able understand tr translate cmd with option -t truncate.
according to man pages -t, --truncate-set1 first truncate SET1 to length of SET2

my work around:

[root@server cg]# echo "hhi hello" | tr -t [hh] [h]
]]i ]ello
[root@server cg]#

even from my abv example, i dont understand what is doing.
if anyone ve better examples, plz let me know.

It forces a one-to-one mapping... and prevents translating characters that have no matching replacement.

In your test, the [hh], gets truncated to [hh... thus every h translated to ].

You need a better test. Try "echo abcde | tr -t abc fg"

Here the "set1" list (abc) gets trunctated to "ab", so every "a" gets translated to "f", every "b" gets translated to 'g". And the output is "fgcde". "c" doesn't get translated as the string abc was truncted to ab.

Without the -t, the "c" gets translated to the last character of set2 - a "g", thus the output is "fggde".