common/*: update pages of some POSIX special built-in utilities (#11956)

* exec, export, readonly, set, shift, trap: replace command descriptions

* exec, exit, export, readonly, set, shift, trap, exec, export: replace example descriptions

* exec, trap: replace "More information" links

* trap: remove prefix "SIG" from some command arguments

Although POSIX allows implementations to specify signal names without
the prefix "SIG", I will choose the most portable form.

* export: replace term

Co-authored-by: Vitor Henrique <87824454+vitorhcl@users.noreply.github.com>

* set: replace term

Co-authored-by: Vitor Henrique <87824454+vitorhcl@users.noreply.github.com>

* export: replace term

Co-authored-by: Vitor Henrique <87824454+vitorhcl@users.noreply.github.com>

* export: replace term

Co-authored-by: Vitor Henrique <87824454+vitorhcl@users.noreply.github.com>

* exec: replace Open Group link

Co-authored-by: Vitor Henrique <87824454+vitorhcl@users.noreply.github.com>

* exit: replace Open Group link

Co-authored-by: Vitor Henrique <87824454+vitorhcl@users.noreply.github.com>

* export: replace Open Group link

Co-authored-by: Vitor Henrique <87824454+vitorhcl@users.noreply.github.com>

* readonly: replace Open Group link

Co-authored-by: Vitor Henrique <87824454+vitorhcl@users.noreply.github.com>

* set: replace Open Group link

Co-authored-by: Vitor Henrique <87824454+vitorhcl@users.noreply.github.com>

* shift: replace Open Group link

Co-authored-by: Vitor Henrique <87824454+vitorhcl@users.noreply.github.com>

* trap: replace Open Group link

Co-authored-by: Vitor Henrique <87824454+vitorhcl@users.noreply.github.com>

* exec: explain environment of child process

Co-authored-by: Vitor Henrique <87824454+vitorhcl@users.noreply.github.com>

---------

Co-authored-by: Vitor Henrique <87824454+vitorhcl@users.noreply.github.com>

pages/linux/exec.md

@@ -1,20 +1,20 @@
 # exec
 
-> Replace the current process with another process.
-> More information: <https://linuxcommand.org/lc3_man_pages/exech.html>.
+> Execute a command without creating a child process.
+> More information: <https://www.gnu.org/software/bash/manual/bash.html#index-exec>.
 
-- Replace with the specified command using the current environment variables:
+- Execute a specific command:
 
 `exec {{command -with -flags}}`
 
-- Replace with the specified command, clearing environment variables:
+- Execute a command with a (mostly) empty environment:
 
 `exec -c {{command -with -flags}}`
 
-- Replace with the specified command and login using the default shell:
+- Execute a command as a login shell:
 
 `exec -l {{command -with -flags}}`
 
-- Replace with the specified command and change the process name:
+- Execute a command with a different name:
 
-`exec -a {{process_name}} {{command -with -flags}}`
+`exec -a {{name}} {{command -with -flags}}`

pages/linux/export.md

@@ -1,20 +1,20 @@
 # export
 
-> Command to mark shell variables in the current environment to be exported with any newly forked child processes.
+> Export shell variables to child processes.
 > More information: <https://www.gnu.org/software/bash/manual/bash.html#index-export>.
 
-- Set a new environment variable:
+- Set an environment variable:
 
 `export {{VARIABLE}}={{value}}`
 
-- Remove an environment variable:
+- Unset an environment variable:
 
 `export -n {{VARIABLE}}`
 
-- Mark a shell function for export:
+- Export a function to child processes:
 
 `export -f {{FUNCTION_NAME}}`
 
-- Append something to the PATH variable:
+- Append a pathname to the environment variable `PATH`:
 
 `export PATH=$PATH:{{path/to/append}}`

pages/linux/trap.md

@@ -1,21 +1,20 @@
 # trap
 
-> Automatically execute commands after receiving signals by processes or the operating system.
-> Can be used to perform cleanups for interruptions by the user or other actions.
-> More information: <https://manned.org/trap>.
+> Execute a command upon an event.
+> More information: <https://www.gnu.org/software/bash/manual/bash.html#index-trap>.
 
-- List available signals to set traps for:
+- List the available event names (e.g. `SIGWINCH`):
 
 `trap -l`
 
-- List active traps for the current shell:
+- List the commands and the names of the expected events:
 
 `trap -p`
 
-- Set a trap to execute commands when one or more signals are detected:
+- Execute a command when a signal is received:
 
 `trap 'echo "Caught signal {{SIGHUP}}"' {{SIGHUP}}`
 
-- Remove active traps:
+- Remove commands:
 
 `trap - {{SIGHUP}} {{SIGINT}}`