So I'm trying to get the first column of comm output using awk
.
I read that Tab was used as a separator for comm so I did:
awk -F"\t" '{print $1}' comm-result.txt
With comm-result.txt containing the output of:
comm -3 file1 file2
But this doesn't seem to work.
This commend takes also the space character as a separator and I get weird results when my files contains multiple spaces.
How can i only get the first column from comm
?
On the Home tab, in the Cells group, click Format. Do one of the following: Under Visibility, click Hide & Unhide, and then click Unhide Rows or Unhide Columns.
awk to print the first column. The first column of any file can be printed by using $1 variable in awk. But if the value of the first column contains multiple words then only the first word of the first column prints. By using a specific delimiter, the first column can be printed properly.
Here, \t is used as a field separator to print the first column of the file. The '-F' option is used to set the field separator. The following output will be produced after running the above commands.
You can use awk 'NR > 1 {print $1}' to get the first column (using any whitespace character as a delimiter while skipping the first line) or sed 1d | cut -d$'\t' -f1 .
"So I'm trying to get the first column of comm output"
The first column of the "comm file1 file2
" output contains lines unique to the file1
. You can skip the post-processing by simply calling comm
with -2
(suppress lines unique to file2
) and -3
(suppress lines that appear in both files).
comm -2 -3 file1 file2 # will show only lines unique to file1
However, if you have no choice but to process a pre-run output of comm
then as Carl mentioned, cut
would be an option:
cut -f1 comm-results.txt
However, this result in empty lines for cases where column 1 is empty. To deal with this, perhaps awk
may be more suitable:
awk -F"\t" '{if ($1) print $1}' comm-results.txt ---- ---------------- | | Use tab as delimiter | +-- only print if not empty
cut(1)
is probably a better choice than awk
for this problem.
You can use comm
with -2
and -3
(as already explained above), or use comm
with grep
like:
grep -o '^\S\+' <(comm file1 file2)
so the output won't contain any trailing spaces. This is useful for non-comm
commands.
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