general_bash_tricks.cheat

% General Bash Tricks

$ file: fdfind . "$(pwd)" -Ltf | sort -u 
$ json-file-or-url: fdfind . "$(pwd)" -Ltf | sort -u | grep \.json
$ mimeapps-list: locate mimeapps.list | head -n1 | xargs -I {} grep -v '\[' {} | grep --color=no . | awk -F '=' '{print $2}' | sed 's/;//g' | sort -u

# string editing 
echo " # --- remove scema from webpage"
site='ftp://www.example.com'; echo ${site#*//}
echo "# remove (pre|suf)fix bash"
string="hello-world";prefix="hell";suffix="ld";echo "${string:${#prefix}:${#string}-${#prefix}-${#suffix}}" 


# find reminders
echo "find only files"
find . ! -type d
echo "cat files using inode in dir (<dir>) with regex (<partitional_file_name>)"
ls -lai <dir> | grep <partitional_file_name> | awk '{print $1}' | xargs -I fn find <dir> -maxdepth 0 -type d -inum fn -exec cat {} 2>/dev/null \;

# xargs reminders
echo "reuse an variable from stdout multiple times"
echo 'test1\ntest2\ntest3' | xargs -r0 /bin/bash -c 'echo "$@"; echo "$@";' ''
echo 'test1\ntest2\ntest3' | xargs -I {} echo {} | while read stuff; do echo "$stuff"; echo "$stuff";done
echo "xargs use with stdin in the middle (last 2)"
echo 'test1\ntest2\ntest3' | xargs -I {} echo '{}'
echo 'test1\ntest2\ntest3' | xargs -I somerandomstring echo 'somerandomstring'


# grep reminders
echo " # --- adding a test file, with content:"
echo "some word\n#some word 2\n\n some word 3 with space\nsupport\nanother one." | tee /tmp/file_that_definitely_did_not_exist.txt 
echo " # --- hide all matches (-v 'some word')"
grep -v 'some word' /tmp/file_*.txt 
echo " # --- get match count (-c 'some word')"
grep -c 'some word' /tmp/file_*.txt 
echo " # --- whole word search (-w 'some word')"
grep -w 'some word' /tmp/file_*.txt 
echo " # --- display the line numbers (-n 'some')"
grep -n 'some'  /tmp/file_*.txt 
echo " # --- match counter limit m[num] (-m1 'some')"
grep -m1 'some' /tmp/file_*.txt 
echo " # --- match pattern with before[num] (-B1 '2')"
grep -B1 '2' /tmp/file_*.txt 
echo " # --- match pattern with after[num] (-A1 '2')"
grep -A1 '2' /tmp/file_*.txt 
echo " # --- match pattern with before and after [num] (-C1 '2')"
grep -C1 '2' /tmp/file_*.txt 
echo " # --- list filenames without the content. (-l 'support')"
grep -l 'support' /tmp/file_*.txt    
echo " # --- grep for output of the regex ('.*2')"
grep -x '.*2' /tmp/file_*.txt  
echo ' # --- grep match starting string ("^some") ("^[string]") '
grep "^some" /tmp/file_*.txt 
echo " # --- grep match ending string ('\.$')"
grep '\.$' /tmp/file_*.txt
echo " # --- use a file for patterns (-f /tmp/zfile_that_pattern.txt)"
echo 'some word 3\nsupport' > /tmp/zfile_that_pattern.txt;grep -f /tmp/zfile_that_pattern.txt /tmp/file_*.txt ;rm /tmp/zfile_that_pattern.txt 
echo " # --- multiple patterns -e 'some word 3' -e 'support'"
grep -e 'some word 3' -e 'support' /tmp/file_*.txt 
echo " # --- get all comments and empty lines with extended grep (-E '^(#|$)')\n # ps. could be usefull with -v"
grep -E '^(#|$)' /tmp/file_*.txt 
echo " # --- cleaning up"; rm /tmp/file_that_definitely_did_not_exist.txt 

# clear screen without clear
echo "\ec"

# rot13 without external packages
cat <file> | tr 'A-Za-z' 'N-ZA-Mn-za-m'

# remove duplicates from or in file (creates a /tmp/tmp.txt to test on)
echo -e 'dup1\ndup2\ndup2   \ndup1' | tee /tmp/tmp.txt
echo "sort, remove dupes and reorder"
sort -u <file>
echo "remove dupes"
awk '!a[$0]++' <file>
echo "remove dupes"
perl -ne 'print if ! $a{$_}++' <file>
echo "remove dupes even if there are %s behind the string"
perl -lne 's/\s*$//; print if ! $a{$_}++' <file>
echo "It deletes duplicate, consecutive lines from a file (emulates \"uniq\")."
sed '$!N; /^\(.*\)\n\1$/!P; D' <file>
echo "remove dupes inline (replaces inside the file)"
perl -i -ne 'print if ! $a{$_}++' /tmp/tmp.txt
echo -e 'dup\ndup\ndup   \ndup' > /tmp/tmp.txt # leaving a file after to test on.

# redirect stderr to stdout
thiscommanddoesnotexist 2>&1 | grep --color command

# open a file within cli
xdg-open <file>

# change xdg-open default program for a file
file_xdg=$(file --mime-type -b <file>)
xdg-mime query default $file_xdg
xdg-mime default <mimeapps-list> $file_xdg
xdg-mime query default $file_xdg

# add a json inline with gron
(gron <file>; echo 'json.<inject_path> = "<inject_value>";') | gron -u


# skip the first lines-to-skip lines from a file and get the rest (n=amount of lines)
tail -n +$((<n-lines-to-skip> + 1)) <file>

# cat a file and stop at the lines from the bottom (n=amount of lines)
head -n -<n-lines-from-bottom-to-stop-printing> <file>

# sort on keys, sort various columns in a csv file by numeric and dictionary order, columns 5 and after as dictionary order
echo -e '2,3,a,9,C\n2,2,b,20,F\n2,2,c,19,Gb,hj\n2,2,c,19,Gb,hi\n2,2,c,19,Ga\n2,2,b,22,Ga\n1,10,b,22,Ga' > tmp_list_that_does_not_exists.csv
echo -e "original: \n$(cat tmp_list_that_does_not_exists.csv)"; 
echo "sorted: "; sort --field-separator=, --key=1,1n -k2,2n -k3,3d -k4,4n -k5d tmp_list_that_does_not_exists.csv
rm tmp_list_that_does_not_exists.csv

# echo, cat, and remove a file with inode (example)
echo 'Hello general_bash_tricks' > '/tmp/sometempfilethatdoesnotexist`pwd`'; inode=$(ls -li /tmp | grep 'pwd' | awk '{print $1}')
echo $inode | xargs -I inodenumber find /tmp/ -maxdepth 1 -inum inodenumber -exec echo {} \; -exec cat {} \; -exec echo "" \; -exec rm {} \;

# *carefully* remove a file with inode and iname
find . -maxdepth 1 -inum $(ls -li $path | grep '<partitional_file_name>' | awk '{print $1}') -exec -exec rm {} \; # by inum
find . -maxdepth 1 -iname '*<partitional_file_name>*' -exec echo {} \; # by iname


# execute commands with sed
echo 'ls -la\nps aux' | sed 's/.*/&/e'

# replace by hex chars with sed (09=\t, 0a=\n, check `man ascii`) 
echo 'test\ttest' | sed 's/\x09/\x0a/g'

# replace an port (all integers) inside old scans
sed 's/:[[:digit:]]\+\//:<new_port>\//g' <file> # place an -i for in-file operations

# replace newlines with sed
echo -n 'test\ntest' | sed ':a;N;$!ba;s/\n/\t/g'

# print all files in the current workdirectory that are printable
find . -type f -exec grep -Iq . {} \; -print | xargs cat


# replace spaces in filename with `_` lowercase
for file in *; do mv "$file" $(echo $file | tr ' ' '_') ; done