<<Anchor(faq11)>>
== How can I print the n'th line of a file? ==
One dirty (but not quick) way is:

{{{#!highlight bash
sed -n "${n}p" < "$file"
}}}

But this reads the entire file even if only the third line is desired, which can be avoided by using the `q` command to quit on line `$n`, and deleting all other lines with the `d` command:

{{{#!highlight bash
sed "${n}q;d" < "$file"
}}}

Or

{{{#!highlight bash
sed "$n!d;q" < "$file"
}}}

Which appears to be faster with all of GNU, busybox and ast-open sed implementations.

Another method is to grab lines starting at `n`, then get the first line of that.

{{{#!highlight bash
<"$file" tail -n "+$n" | head -n 1
}}}

As that uses more specialized tools, that's generally generally significantly faster.

Another approach, using [[AWK]]:

{{{#!highlight bash
awk -v n="$n" 'NR==n{print;exit}' < "$file"
}}}

If more than one line is needed, it's easy to adapt any of the previous methods:

{{{#!highlight bash
x=3 y=4
sed "$x,$y!d;${y}q" < "$file"                          # Print lines $x to $y; quit after $y.
tail -n "+$x" < "$file" | head -n "$(( y - x + 1 ))"   # Same, generally faster
awk -v x="$x" -v y="$y" 'NR>=x; NR==y{exit}' < "$file" # Same, generally slower
}}}

Or a counter with a simple `read` loop, though that's going to be orders of magnitude slower for any input with more than a few hundred lines.

{{{#!highlight bash
# Bash/ksh/zsh
{
    m=0
    while ((m++ < x - 1)) && read -r _; do
        :
    done

    head -n "$((y - x + 1))"
} < "$file"
}}}

To read into a variable, it is preferable to use `read` or `mapfile` aka `readarray` rather than an external utility. More than one line can be read into the given array variable or the default array `MAPFILE` by adjusting the argument to mapfile's -n option:

{{{#!highlight bash
# Bash4
{
  mapfile -s "$((x - 1))" -n "$((y - x + 1))" lines
  printf %s "${lines[@]}"
} < "$file"
}}}

=== See Also ===
 * [[BashFAQ/001]]
 * http://wiki.bash-hackers.org/commands/builtin/mapfile
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CategoryShell