$ ar
Usage: ar [emulation options] [-]{dmpqrstx}[abcfilNoPsSuvV] [member-name] [count] archive-file file...
       ar -M [<mri-script]
 commands:
  d            - delete file(s) from the archive
  m[ab]        - move file(s) in the archive
  p            - print file(s) found in the archive
  q[f]         - quick append file(s) to the archive
  r[ab][f][u]  - replace existing or insert new file(s) into the archive
  t            - display contents of archive
  x[o]         - extract file(s) from the archive
 command specific modifiers:
  [a]          - put file(s) after [member-name]
  [b]          - put file(s) before [member-name] (same as [i])
  [N]          - use instance [count] of name
  [f]          - truncate inserted file names
  [P]          - use full path names when matching
  [o]          - preserve original dates
  [u]          - only replace files that are newer than current archive contents

 generic modifiers:
  [c]          - do not warn if the library had to be created
  [s]          - create an archive index (cf. ranlib)
  [S]          - do not build a symbol table
  [v]          - be verbose
  [V]          - display the version number
 emulation options:
  No emulation specific options
ar: supported targets: pe-i386 pei-i386 elf32-i386 elf32-little elf32-big srec symbolsrec tekhex binary ihex

e.g:
# partially link file (for dynamic download & linking)
# and add it to library for static linking
$(COMP_OBJ): $(TMP_COMP_OBJS)
 @$(ECHO) Linking $@
 $(MDBG)$(LD) -r -o $@ $(TMP_COMP_OBJS)
ifeq ($(SINGLE_FILES_TO_LIB),yes)
  @$(ECHO) Adding $(TMP_COMP_OBJS) to library $(OUTPUT_LIB1)
  $(MDBG)$(MYAR) -dc $(LIBOUTPUT_DIR)/$(OUTPUT_LIB1) $(TMP_COMP_OBJS)
  $(MDBG)$(MYAR) -qc $(LIBOUTPUT_DIR)/$(OUTPUT_LIB1) $(TMP_COMP_OBJS)
else
  @$(ECHO) Adding $@ to library $(OUTPUT_LIB1)
  $(MDBG)$(MYAR) -dc $(LIBOUTPUT_DIR)/$(OUTPUT_LIB1) $(notdir $@)
  $(MDBG)$(MYAR) -qc $(LIBOUTPUT_DIR)/$(OUTPUT_LIB1) $@
endif
ifeq ($(OUTPUT_OWN_LIB),yes)
  @$(ECHO) Adding $(TMP_COMP_OBJS) to own library $(COMP_NAME).a
  $(MDBG)$(RM) $(LIBOUTPUT_DIR)/$(COMP_NAME).a
  $(MDBG)$(MYAR) -rc $(LIBOUTPUT_DIR)/$(COMP_NAME).a $(TMP_COMP_OBJS)
endif