taiyebur taiyebur - 1 year ago 127
Linux Question

Why is there extra output when using newline as IFS?

I was testing the output for different values of IFS using the code below.



export $IFS

for i in $(ls -la);
echo $i;

But for newline as IFS the following things were also printed before the intended output. Why does it show this output?

declare -x DBUS_SESSION_BUS_ADDRESS="unix:abstract=/tmp/dbus-xwjTMGqSe7,guid=b8543bd3ba7dbc5ca284b0ce5741ccff"
declare -x DESKTOP_SESSION="default"
declare -x DISPLAY=":0"
declare -x GDMSESSION="default"
declare -x GDM_LANG="en_US.utf8"
declare -x GIO_LAUNCHED_DESKTOP_FILE="/usr/share/applications/atom.desktop"
declare -x GJS_DEBUG_OUTPUT="stderr"
declare -x GNOME_DESKTOP_SESSION_ID="this-is-deprecated"
declare -x GPG_AGENT_INFO="/run/user/1000/keyring/gpg:0:1"
declare -x LANG="en_US.utf8"
declare -x NODE_ENV="production"
declare -x NODE_PATH="/usr/share/atom/resources/app.asar/exports"
declare -x OLDPWD
declare -x PATH="/usr/local/bin:/usr/bin:/bin:/usr/local/games:/usr/games"
declare -x SHELL="/bin/bash"
declare -x SHLVL="1"
declare -x SSH_AGENT_PID="2218"
declare -x SSH_AUTH_SOCK="/run/user/1000/keyring/ssh"
declare -x WINDOWPATH="7"
declare -x XDG_DATA_DIRS="/usr/share/gnome:/usr/local/share/:/usr/share/"
declare -x XDG_MENU_PREFIX="gnome-"
declare -x XDG_RUNTIME_DIR="/run/user/1000"
declare -x XDG_SEAT="seat0"
declare -x XDG_SESSION_DESKTOP="default"
declare -x XDG_SESSION_ID="1"
declare -x XDG_VTNR="7"

Answer Source

Because of the dollar sign in the export command.

Due to your assignment, $IFS will expand to a newline, which, without quotes, will simply be dropped by the shell, leaving the export command on its own with no arguments.

And according to help export:

export: export [-nf] [name[=value] ...] or export -p
  If no NAMEs are given, or if `-p' is given, a list of
  all names that are exported in this shell is printed.

Which is exactly what happens.

To fix that, just leave the export command off altogether, as it's not required (thanks, kojiro).

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