Text snippet creator/manager in Bash

Question

Below is a script to create and manage text snippets. It is also posted on GitHub. Most of the code is error checking and displaying help because I wanted to make a solid command line interface. The blanks function is used when copying a snippet with a blank (@) character in it. The user fills in the blanks.

I am looking for a review of the script: Is it easy to use? Is the code confusing? Are there any horrible bugs that I left unnoticed?

It is tested in OS X, so I am not sure if the syntax will work elsewhere. Specifically, the pbcopy and pbpaste aliases are untested.

#!/bin/sh list() { echo "snp snippets:\n" echo "$(ls -R $snippets_dir)" } move() { if [[ "$2" == "" && $3 == "" ]]; then echo "snp usage:\n" echo "snp move <name> <group>" elif [[ -e $snippets_dir/$2 ]]; then if -d $snippets_dir/$3 ]]; then mv $snippets_dir/$2 $snippets_dir/$3/$2 else echo "ERROR: Group $snippets_dir/$3 does not exist."; exit 1 fi else echo "ERROR: Snippet $2 does not exist."; exit 1 fi } new() { if [[ "$2" == "" && "$3" == "" ]]; then echo "snp usage:\n" echo "snp new <name> \"<text>\"" echo "snp new group <name>" elif [[ "$2" == "group" || "$2" == "g" ]]; then # New group if [[ "$3" != "" ]]; then mkdir $snippets_dir/$3 echo "Created new group \"$3\"." else echo "snp usage:\n" echo "snp new group <name>" fi else # New snippet if [[ "$2" == "" ]]; then echo "snp usage:\n" echo "snp new <name> \"<text>\"" else if [[ -e $snippets_dir/$2 ]]; then echo "Snippet $snippet_dir/$2 already exists." echo "Overwrite? [y/n]" read yn if [[ $yn == "y" || $yn == "Y" ]]; then rm $snippets_dir/$2 else return fi fi printf "$3" >> $snippets_dir/$2 echo "Created new snippet \"$2\"." fi fi } remove() { if [[ "$2" == "" ]]; then echo "snp usage:\n" echo "snp remove <name>" echo "snp remove group <name>" elif [[ "$2" == "group" || "$2" == "g" ]]; then # Remove group if [[ "$3" != "" ]]; then if [[ -e "$snippets_dir/$3" ]]; then rm -rf $snippets_dir/$3 echo "Removed group \"$3\"." else echo "ERROR: Group $3 does not exist."; exit 1 fi else echo "snp usage:\n" echo "snp remove group <name>" fi elif [[ "$2" != "" ]]; then # Remove snippet if [[ -e $snippets_dir/$2 ]]; then rm $snippets_dir/$2 echo "Removed snippet \"$2\"." else echo "ERROR: Snippet $2 does not exist."; exit 1 fi fi } blanks() { data=$(cat $1) count=0 OIFS=$IFS IFS="@" blanx=$(echo "$data" | tr -d -c '@' | wc -c | awk '{print $1}') result="" for x in $data; do if [ $count -eq $blanx ]; then echo "$x" result="$result$x" break fi echo "$x" result="$result$x" read -p"snp> " v result="$result$v" count=`expr $count + 1` done IFS=$OIFS printf "$result" >> $1-tmp } copy() { if [[ "$1" == "" ]]; then usage elif [[ -e $snippets_dir/$1 ]]; then if [ ! $(uname -s) = "Darwin" ]; then alias pbcopy='xsel --clipboard --input' fi blanks $snippets_dir/$1 cat $snippets_dir/$1-tmp | pbcopy echo "Snippet text copied to clipboard." rm $snippets_dir/$1-tmp else echo "ERROR: Snippet $1 does not exist."; exit 1 fi } paste() { if [[ "$2" == "" ]]; then usage elif [[ -e $snippets_dir/$2 ]]; then if [ ! $(uname -s) = "Darwin" ]; then alias pbcopy='xsel --clipboard --input' alias pbpaste='xsel --clipboard --output' fi blanks $snippets_dir/$2 cat $snippets_dir/$2-tmp | pbcopy pbpaste rm $snippets_dir/$2-tmp else echo "ERROR: Snippet $2 does not exist."; exit 1 fi } usage() { echo "snp usage:\n" echo "snp <name> # Copy snippet to clipboard" echo "snp paste <name> # Paste name (from clipboard)" echo "snp new <name> \"<text>\" # New snippet" echo "snp new group <name> # New group" echo "snp list # List snippets" echo "snp move <name> <group> # Move snippet to group" echo "snp remove <name> # Remove snippet" echo "snp remove group <name> # Remove group" echo "snp help # Display usage" } snippets_dir=~/".snp" # Check for/create snippet dir if [[ ! -d $snippets_dir ]]; then echo "ERROR: $snippets_dir doesn't exist." echo "Create it now? [y/n]" read yn if [[ $yn == "y" || $yn == "Y" ]]; then mkdir $snippets_dir echo "$snippets_dir created" else exit 0 fi fi case $1 in p|paste) paste "$@" ;; n|new) new "$@" ;; l|list) list ;; m|move) move "$@" ;; r|remove) remove "$@" ;; h|help) usage ;; *) copy "$@" ;; esac exit 0 

Answer 1

Overall

• You're using some bash-specific things ([[ ... && ... ]]), so your shebang line should be #!/bin/bash
• very good indentation, readable code
• more quotes: mv "$snippets_dir/$2" "$snippets_dir/$3/$2"

list function

• ls knows how to print to the screen, don't need echo $(ls ...)

move function

• you need echo -e if you want \n to be interpreted as a newline.
• syntax error on 2nd if, missing [[

new function

• if you use outer single quotes, don't need to escape inner double quotes (unless you need variable interpolation, of course)
• I would test for "yes" like this: if [[ ${yn,} == y* ]] -- see http://www.gnu.org/software/bash/manual/bashref.html#Shell-Parameter-Expansion

blanks function

• declare local variables with local
• to read content from a file in bash: data=$(< "$1")
• bash can do arithmetic: (( count++ )) -- see http://www.gnu.org/software/bash/manual/bashref.html#Conditional-Constructs

• you only ever use this function to copy stuff to the clipboard, so you don't need a temp file:

  blanks "$snippets_dir/$1" | pbcopy 

• don't use printf "$astring" -- if $astring contains %-directives you'll get "not enough arguments" errors. Stick to echo, or if you're specifically avoiding a trailing newline, printf "%s" "$astring"

paste function

• I would use case here, if you decide you need OS-specific aliases:

  case $(uname -a) in Darwin) : ;; *) alias pbcopy='...' alias pbpaste='...' ;; esac 

Answer 2

I am not a great fan of fall-through logic ... if there is an argument issue (missing argument, whatever), you are falling through the work functions, and letting the program end. I would make this more explicit with an exit 3. Programs should always set an exit code unless they successfully complete. I don't consider argument errors to be a successful completion.

aside - Bash has some reserved exit codes, which you should typically not use. 1 is one of the reserved exit codes. As a result, try to use values other than 1 or 2 for exit codes from shell scripts....

I would recommend creating an error-handling function... something along the lines of:

generalerror() { echo "snp usage:" echo $1 echo usage exit 3 } checkargument() { if [[ "$1" == "" ]]; then generalerror $2 fi } 

This will allow you to centralize a lot of your error handling with some simpler messages/handling... the reason I am suggesting this is because of the following:

remove() { if [[ "$2" == "" ]]; then echo "snp usage:\n" echo "snp remove <name>" echo "snp remove group <name>" elif [[ "$2" == "group" || "$2" == "g" ]]; then # Remove group if [[ "$3" != "" ]]; then if [[ -e "$snippets_dir/$3" ]]; then rm -rf $snippets_dir/$3 echo "Removed group \"$3\"." else echo "ERROR: Group $3 does not exist."; exit 1 fi else echo "snp usage:\n" echo "snp remove group <name>" fi 

That code does not exit 1.... probably because it was just an oversight... and this is why functions are good ;-)

The above code could be:

remove() { checkargument $2 "snp remove <name>\nsnp remove group <name>" if [[ "$2" == "group" || "$2" == "g" ]]; then # Remove group checkargument $3 "snp remove group <name>" .... 

Right, then your error handling:

cat $snippets_dir/$1-tmp | pbcopy 

The above line is critical to your program.... but, it does not check for errors.... Did the pbcopy succeed?

So:

• functions to extract common logic are useful....
• exit code set for bad values.
• different exit code for functional problems ... (failed sub-commands)
• error handling!