Bash – Display the function body in Bash

bashfunction

I have setup several functions in my .bashrc file. I would like to just display the actual code of the function and not execute it, to quickly refer to something.

Is there any way, we could see the function definition?

Best Answer

The declare builtin's -f option does that:

bash-4.2$ declare -f apropos1
apropos1 () 
{ 
    apropos "$@" | grep ' (1.*) '
}

I use type for that purpose, it is shorter to type ;)

bash-4.2$ type apropos1
apropos1 is a function
apropos1 () 
{ 
    apropos "$@" | grep ' (1.*) '
}

Related Solutions

Bash Function – How to Redefine a Bash Function in Terms of Old Definition

You can print out the current definition of the function, and then include it in a function definition inside an eval clause.

current_definition=$(declare -f command_not_found_handle)
current_definition=${current_definition#*\{}
current_definition=${current_definition%\}}
prefix_to_add=$(cat <<'EOF'
  # insert code here (no special quoting required)
EOF
)
suffix_to_add=$(cat <<'EOF'
  # insert code here (no special quoting required)
EOF
)
eval "command_not_found_handle () {
  $prefix_to_add
  $current_definition
  $suffix_to_add
}"

Another approach, which I find clearer, is to define the original function under a new name, and call that from your definition. This only works if you don't need to act on the local variables of the original definition.

eval "original_$(declare -f command_not_found_handle)"
command_not_found_handle () {
  …
  original_command_not_found_handle
  …
}

Bash Function Decorator

That would be a lot easier with zsh that has anonymous functions and a special associative array with function codes. With bash however you could do something like:

decorate() {
  eval "
    _inner_$(typeset -f "$1")
    $1"'() {
      echo >&2 "Calling function '"$1"' with $# arguments"
      _inner_'"$1"' "$@"
      local ret=$?
      echo >&2 "Function '"$1"' returned with exit status $ret"
      return "$ret"
    }'
}

f() {
  echo test
  return 12
}
decorate f
f a b

Which would output:

Calling function f with 2 arguments
test
Function f returned with exit status 12

You can't call decorate twice to decorate your function twice though.

With zsh:

decorate()
  functions[$1]='
    echo >&2 "Calling function '$1' with $# arguments"
    () { '$functions[$1]'; } "$@"
    local ret=$?
    echo >&2 "function '$1' returned with status $ret"
    return $ret'

Best Answer

Related Solutions

Bash Function – How to Redefine a Bash Function in Terms of Old Definition

Bash Function Decorator

Related Question