Question

please provide me a sed oneliner which provides this output:
sdc3 sdc2
for Input :
sdc3[1] sdc2[0]

I mean remove all subscript value from the string ..

Answer 1

sed 's/\[[^]]*\]//g'

reads: substitute any string with literal “[” followed by zero or more characters that aren’t a “]”, and then the closing “]”, with an empty string.

You need the [^]] bit to prevent greedy matching treating “[1] sdc2[0]” as a single match in your sample string.

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As for your comment:

sed 's#\([^[ ]*\)\[[^]]*\]#/dev/\1#g'

• I switch the seperator from the usual ‘/’ to ‘#’, just to avoid escaping the /dev/ bit you asked for (I won’t say “for clarity”)
• the \(...\) bit matches a subgroup, here sdc2 or whatever, so we can refer to it in the replacement
• the subgroup uses a similar character class to the one we used discarding the index: [^[ ] means any character except an “[” (again, to avoid greedily matching the index) or a space (assuming your values are space-delimited as per your post)
• the replacement is now the literal “/dev/” followed by the first (and only) subgroup match
• the g flag at the end tells it to perform multiple matches per line, instead of stopping at the first one