( /unixhelp/unixshell.txt )
shell * 1. shell * 1_1. - 1_2. 1_3. 1_4. , * 2_ shell * 2_1. 2_2. 2_3. 2_4. * 3_ * 3_1. 3_2. 3_3. . 3_4. 3_5. 3_6. 3_7. * 4_ shell- * 4_1. shell 4_2. 4_3. 4_4. 4_5. * 5_ * 5_1. test 5_2. expr 5_3. ena