Useful bash commands

commands.sh

# gets fileName.ext from /path/to/fileName.ext. if it's /path/to, it gets 'to'
file_name_w_ext=$(basename "$1")
# gets fileName from the given file
file_name="${file_name_w_ext%.*}"

# gets directory path 
file-path=$(dirname "$1")

# collapse multiple columns into a single column (leaving the first column)
awk '{for(i=2;i<=NF;i++) {print $i}}' infile.txt > infile_col_collapse.txt

# sort, uniq
sort infile.txt | uniq > infile_uniq.txt

# find common lines between two files - each file has a single column. Here -1 suppresses lines unique to file_one and
# -2 suppresses lines unique to file_two, retaining only the common lines
comm -12 file_one file_two > common_lines.txt

# combine multiple images to one image. +append helps add images horizontally
convert -density 300 +append file1.pdf file2.pdf file3.pdf output.pdf

# images can also be combined using montage. This creates a 2x3 grid (2 rows by 3 columns)
montage -density 300 -geometry +0+0 -tile 3x3 file1.pdf file2.pdf file3.pdf file4.pdf file5.pdf file6.pdf output.pdf

# for each line in a text file, do something. Here for each line, we list the file and get the size and name of file.
ls -lh $(<file.txt) | awk '{print $5, $9}'

# another version of above
while read in; do ls -lh "$in" | awk '{print $5,$9}'; done < file.txt

# for each line in file (expects two columns, 2nd column being path to a file), copy the interest file to another location
cut -f2 file.txt | while read ln; do cp $ln /path/to/destination/; done

# grep a file for all the strings in another file 
grep -f strings_to_search.txt file_to_be_searched.txt > matched_strings.txt

# look up process ID for a task running on a port (9989)
lsof -i :9989 | grep LISTEN