How do I read the first line of a file using cat?
BashFile IoCatBash Problem Overview
How do I read the first line of a file using cat?
Bash Solutions
Solution 1 - Bash
You don't need cat.
head -1 file
will work fine.
Solution 2 - Bash
You don't, use head instead.
head -n 1 file.txt
Solution 3 - Bash
There are many different ways:
sed -n 1p file
head -n 1 file
awk 'NR==1' file
Solution 4 - Bash
You could use cat file.txt | head -1, but it would probably be better to use head directly, as in head -1 file.txt.
Solution 5 - Bash
This may not be possible with cat. Is there a reason you have to use cat?
If you simply need to do it with a bash command, this should work for you:
head -n 1 file.txt
Solution 6 - Bash
cat alone may not be possible, but if you don't want to use head this works:
cat <file> | awk 'NR == 1'
Solution 7 - Bash
I'm surprised that this question has been around as long as it has, and nobody has provided the pre-mapfile built-in approach yet.
IFS= read -r first_line <file
...puts the first line of the file in the variable expanded by "$first_line", easy as that.
Moreover, because read is built into bash and this usage requires no subshell, it's significantly more efficient than approaches involving subprocesses such as head or awk.
Solution 8 - Bash
You dont need any external command if you have bash v4+
< file.txt mapfile -n1 && echo ${MAPFILE[0]}
or if you really want cat
cat file.txt | mapfile -n1 && echo ${MAPFILE[0]}
:)
Solution 9 - Bash
Use the below command to get the first row from a CSV file or any file formats.
head -1 FileName.csv
Solution 10 - Bash
There is plenty of good answer to this question. Just gonna drop another one into the basket if you wish to do it with lolcat
lolcat FileName.csv | head -n 1
Solution 11 - Bash
Adding one more obnoxious alternative to the list:
perl -pe'$.<=1||last' file
# or
perl -pe'$.<=1||last' < file
# or
cat file | perl -pe'$.<=1||last'