Functions dim, nrow, and ncol for shell

Ever wanted to find out quickly the number of rows and/or columns in file directly from terminal. There are many ways to skin this cat. Here is what I used for number of rows for quite a while:

wc -l filename

What about number of columns? "Easy", just combine head and awk commands:

head -n 1 filename | awk '{ print NF }'

not a big problem (there are likely better ways to do this), but is long and tedious.

I got sick of typing commands above and assembled them in three easy to use function with R-like names: nrow, ncol, and dim. Functions are simply a collection of above ideas and assume that the file is of "rectangular shape", i.e., a table, a matrix, etc.

  for FILE in $@; do
    NROW=$(nrow $FILE | awk '{ print $1}')
    NCOL=$(ncol $FILE | awk '{ print $1}')
    echo "$NROW $NCOL $FILE"
    unset NROW NCOL
export -f dim

nrow ()
  for FILE in $@; do
    wc -l $FILE
export -f nrow

ncol ()
  for FILE in $@; do
    TMP=$(head $FILE -n 1 | awk '{ print NF }')
    echo "$TMP $FILE"
    unset TMP
export -f ncol

Add these files to your .bashrc or .profile or something similar and you can now simply type:

nrow filename
ncol filename
dim filename

A simple test:

touch file.txt
echo "line1 with four columns" >> file.txt
echo "line2 with four columns" >> file.txt

nrow file.txt
2 file.txt

ncol file.txt
4 file.txt

dim file.txt
2 4 file.txt


Recover deleted file under linux

Here is a nice summary, but the bottom line is that the Ubuntu/Debian package testdisk has a nice utility called photorec that can be used to search for deleted files and recover. This is not a GUI program, though!